I just had a situation in a campaign mission where, after the cut-scence that removes all buffs, the char was standing directly in the middle of a whole bunch of chaos marines and a ton of trash mobs and even reacting fast and getting in some distance it was barely manageable to not die, and that was not on a really high difficulty either.

I have a strong feeling that the devs don't know their own game as much as they should, or such a failure would not have gone unnoticed.