I'm not looking at this from a powerplay perspective I'm looking at this from an roleplay perspective.
If the stat for carnage would be called wisdom I would not have a problem with it.
Its the fact that If you want to go "all out" on carnage and make a full carnage barbarian you would have to make him an intellectual.
A barbarian that spend his whole life training his skills with a sword while the mage was studying books during his should not be equally smart.
Some people see attributes and they see damage numbers BUT others like me see tools in them to create a character from their imagination
that's where an intellectual Barbarian becomes a problem.
I played WHFRP 2e a few days ago and I thought to myself I want to make a slayer like character!
A full carnage based barbarian would be a great fit... almost perfect BUT I don't want him to be an intellectual BUT I do want to increase the range of his carnage.
If carnage range would be a Skill instead of an Attribute that would fit better or an attribute called wisdom instead of intellect.
It would be okay if he would be capable to survive in the wild because of his wisdom but he should not outsmart a wizard or beat him in a game of chess.
I love PoE its a great game with a great Battlesystem It makes it hard for me to go back to BG1+2, IWD1+2 and so on BUT its because of how great it works for battles.
When it comes to roleplay and imagination it also does the job pretty well, kudos to the designers but it falls a little bit apart when you get to the intellectual barbarian...