It's not "unfair" to have multiple enemies attacking at once
When was this ever a problem in an RPG?
Was it a problem in BG or Fallouts? No. Might and Magic? No. Bethesda? No. Any FPS ever made? No.
Was it ever a problem, in any game? wtf
I think you fundamentally don't understand that genre of games. Your complaints are kind of what it looks like when people complain about turn-based games because "why can't I just go up to him and hit the enemy when he's just standing there?".
Spectacle action, character action, DMC-like, whatever we decide to call the genre, works in a way that makes it a logical choice to make enemies usually not attack at the same time. For one thing, you're supposed to not get hit. In a majority of RPGs you're inevitably get hit sometimes, to give armor, endurance, evasion and such stats a reason to exist. In an FPS you're going to get hit unless you circle strafe or use cover or such. In a third person action game like GoW or DMC, you're usually surrounded by several enemies. It would be weird if you're fighting the armies of Hell of some other mythological place and they only send one enemy at a time at you. You need to design the game so that it's possible to find openings in between enemy attacks, because you need to be able to dodge or block them, and failure to do so usually leads to taking a lot of damage (on top of losing your combo/stylish rank etc.). The solution is to have several enemies, but stagger their attacks somewhat. And before you say it, that's not the same as having only one enemy, because you still need to be ready for an attack from any of the enemies around you, and watch out for any of the other enemies attacking you while you're attacking one enemy. All the enemies are active threats; they just aren't attacking at the exact same instance, most of the time.
Another factor is that many actions tend to animation lock or root you, to some degree. That's either not relevant or not true in RPGs or FPS games. You can shoot, reload, and usually melee while moving in an FPS, so you're constantly moving. And as for Thief, that's a completely different genre. If you've alerted not one, but several guards in Thief, you've failed because Thief is a stealth game. Being surrounded by enemies is basically the default combat encounter in a game like GoW.
Does this apply to Avowed? No idea, I haven't watched any footage of it. But you were talking about action games in general, not specifically Avowed. And like I said, I think you just fundamentally don't understand how such action games work (whether you consider them good or not being irrelevant).