@ematt84
I used a controller about 90% of my playtime, and I think it's overpowered (started in march 2019), still use one.
While it's true that both input devices have their unique features (without steam profiles), it doesn't necessarily mean they will physically use them. Ability to do something, doesn't mean that person will use it, just means they have access to it (just look at what the internet is mostly used for, mostly never for learning...).
Most m&k users will never use an entire desk just to game, So using the argument of arm vs thumb is nonsensical as most m&k users use their wrist.
I personally like playing DayZ (PC) with a controller even though I have access to a mouse & keyboard, as I just find it more enjoyable. Am I at a loss?, I don't think so. While I also think controllers are more enjoyable, I do not think I deserve aim assistance just to compete with m&k users.
Gaming is meant to be fun, but at what cost to others?
To me, this whole notion of aim assistance and its inclusion or not is a mixture of when businesses use the false notion of accessibility in form of a marketing ploy.
Video game companies want you to feel better about yourself as quickly as possible in a free 2 play title so you're more likely to spend money. Aim assistance plays a role in that. It's not about accessibility and/ or integrity, it's just business.
I don't understand your notion of aiming with a controller without aim assistance. I think the controller is perfectly fine to aim, even without aim assistance (well depends on the user's practice and/ or overall ability I guess).