I think I misread what you meant by damage turning into 100-200, thought you meant weapon values not actual DPS.

They kind of explained the reasoning as over inflation of damage as the justification against having inflation. Which within a mission based game i'm personally ok with as I think it brings more to the game than it takes away. The tough thing will be getting people to accept that a power levels represent an "are you ready yet" check that mean players will have to invest x amount of time into each area before they progress into the next region. Not specifically anything to do with your characters particular capabilities. 

While I understand its a pretty important to many players that they constantly see their damage numbers go up as from a lot of traditional ARPGS (looking at you D3) that's literally the only reason to invest time into the game, it's fairly clear that isn't the intention for inquisitor, as well as being loot focused there are other ambitions to make characters want to play..

While i'm sure many will dislike the idea of it I can see why it's being done... inflation of damage is one of the biggest issues with the ARPG genre and to me at least really detracts from the experience. One eg would be that my cabal are currently all playing D3 due to lack of anything else to do... and none of us have comparable damage levels, someone is always being carried.... someone is always overleveled, and then you get one item and boom your damage goes up 400% ... ultimately having every power level as a tier would lead to this sort of issue as well as the worthless PvP that diablo tired to impliment which was plagued by the same issues.

Not sure if you were aware of this but there are modifiers in the game that mean that each +1 power level you are against that you do -X% damage to them. That's the difference between each power level. The enemy health and your damage remains a constant value but there is an internal difficulty setting tied to each of them. So against power level +1 you do -10% damage, +2 would be -20% damage etc. So yes, you need to progress in power level to technically "do more damage" - but it isn't via increasing the damage value of the weapon. It's via the matching the difficulty of the content. 

If we didn't have power levels at the moment, which represent a range of 1-15 difficulty levels, then there would be no point in having 15 planets and various stories in each sector, all of those planets would be instantly playable and the idea of progressing through an area would be lost. Sure, a traditional game would make each planet increasingly difficult by increasing mob health. Players ergo chase bigger numbers to deal with that health. Martyr has just done it another way, where the enemy health remains a constant but your damage against the 1-15 levels will vary depending on how much higher it is than yourself. Ultimately it's the same outcome, only the player doesn't get the benefit of seeing bigger numbers. The end experience though is exactly the same, playing through content in an intended order to follow whatever story or content etc that they lay out for us.

I think you misunderstand one key feature of the power level. The +% is only relative to your own power level. So when you are level 2 vs 4 for eg then you are +2 difficulty. Someone who is power level 7 vs 13 for eg is playing at +6 power level difficulty. What happens is the power level % is based on your own character, not on a scale of 0-15. So as you progress in power levels, you can progress in content, while doing the same damage. It's ultimately a very simple calculation and no spreadsheets are required... The same build at power level 5 will be good at power level 10, with the same stats, provided they are = in power level to the content you are playing at. 

As a result i'm not quite sure how 10-20 power levels contractions having damage inflation. You can take any player from power level 1-20 and their weapon will be 90-110 damage, which ultimately means you can throw any of them into a game together and they will be able to play and share the same experience. Only each of them might be at a different power level and at a different part of the progression, which again becomes irrelevant when the hosts power level is used to calculate the difficulty.  

You are correct. Every one of those variables stays the same, your damage, your health and your weapons DPS. The only thing that changes is your power level. Not by a slider, but by gathering gear with higher attack rating - this will go towards your total power level. But has no impact on your characters damage output as a raw value.

It's best explained in this EG. 

• You are power level 2. Doing 350 DPS. 
• You choose to fight vs a level 3 mission, doing -20% damage and taking +20% damage (because +1 power level = +1 difficulty)
• While doing these missions you will be gathering gear that progresses you from the current power level to the next, irrespective of which power level planet you are playing on, you will always gather gear from your current attack power range. Basically playing level 4 planets doesn't give you level 4 gear, playing as a level 4 gear anywhere gives you level 4 gear. By "progresses" this means gear that is the same in every way except it has more attack rating
• When you gather enough to make you power level 3, you no longer have the +/-20% damage penalty vs level 3 missions and instead this same penalty is moved to power level 4. The items however will be of the exact same loot table and ranging within the exact same values. Ergo your damage = the same. The power level modifier will just shift in accordance with your equipment attack rating (which determines your power level). 
  
  Hope that clears it up.  

If you want difficulty you play vs a higher power level. 

Level 1 vs Level 2 = Doing 20% less damage and taking 20% more for eg.
Level 1 vs level 3 = Doing 30% less damage and taking 30% more for eg.
These number is made up for the moment but I have them written down somewhere..
The hosts power level vs the mission power level determins the difficulty and no-one else

In the above EG lets say you are level 2 and you have buck buck and buck in your party who are level 3.
You choose to play a level 3 mission. It's +1 power level from you. So everyone has the +1 difficulty penalty applied to them. 

Fortunately because of the power level system, you all have gear from the same damage range anyway... As only the hosts power level is taken into consideration you all get to do the same damage and have the same difficulty rating.

It's actually really simple. Power level = an external % modifyer added. But the DPS / Damage ranges are the same "per Tier" - you just have to continually grind new gear sets which raise your power level. But they don't increase your raw damage, they just "unlock" the next difficulty by lowering the modifyers a stage.

Key point i'm making in that video is that Creep isn't evil..... Creep in large quantities has tangible negative effects on a game. 

Well if you skip to do power level 20 missions with your friend who is 20 and hosting (assuming P20 is the end of the first Tier) you still gather gear at "YOUR" current power level and why i took some care to emphasize this, so if you are level 3 you will be getting level 3 gear. Either way you have to level up 20 times and either way it'll take the same pace. That's the advantage of the system, it's an invisible roadblock that you have to smash several times in order to get some A-B. Some players will see that as pointless but it has the same effect as any other game that "unlocks" more content as you go along. It's safe to assume the story content will be required to unlock new areas and missions, which then ahve to be done to get to the next area.. these will be single player only and ergo you will have to work on your power level to meet the requirements to do these too :)

In regards to your comment as to DPS increasing... "kinda" - your damage is the same. The modifier or calculation it goes through differs. While the outcome seems similar it's so important to recognize the difference. In terms of power creep this is the whole point. EG time!

IM System - Lets say me and my group of friends all have 100-110 damage on our weapon. We go in a mission and even if it's +50% damage due to picking something very easy... we are in a very narrow range of damage, to the point it won't impact gameplay. Friends of another Tier will have more or less but odds are that as each Tier will take a few weeks you will all have this in common, meaning during those weeks you can all play together. 

Classic system - My friend invests 20% more time than me and managed to get to 5 levels higher than me. Lets say each level raises weapon damage by 5% (being modest) and we cast Fireball that does 200% weapon damage. We can both accept this is how most ARPGS will work. Now we have a situation where not only is he gaining another 25% weapon damage over me, he then has that doubled for the fireball skill and now he is doing 50% damage more than me. Unfortunately 5% is just a dream and in most ARPGS that number will be 10 fold, meaning slight differences in player level or gear make massive difference in numerical changes. The real difference is that gear only scaling up once every 20 power levels instead of every power level means the damage spread is 20 times smaller, which reduces the range of damage notably and I think at least... is a good think for a game that wants to promote co op.

I'd presume the damage scale would be far slower as that's their purpose of having the system, probably something like

T1 - 90-110
T2 - 100-120

etc etc - I'm making the assumption of some overlap but there might not be.

Not quite sure what your question was tho :D

I think you may have mis-read the post. Power levels do not correlate with an increase in damage so the whole of Level 1-15 for eg is going to be the same damage range. It'll only increase once when you step up a tier. Thus why it's a tiered progression, pretty different to anything we are used to. Again jsut to quote them this entire system has been designed to avoid DPS inflation. If anything more people will complaint that there is a lack of inflation.