Should there be a restraint on shit that breaks the overall feel of the game like the cat pyjamas or the medic hairy chest? Yeah probably but if you took every hat ever added to tf2 i feel like the ones people call "artstyle breaking" are a very small minority compared to the ones that fit the artstyle.
first and foremost you should cover your definition of what makes something "artstyle breaking", since if you just say "it's not something fitting of the americana style" then i got shit to work with, especially since there's plenty of good and bad hats that fit the americana style but still break the artstyle of the game (and vice versa) since all of the hats have to answer these three extra questions:
- does it respect team recognition?
- is the character in question still recognizable with the cosmetics on?
- do you think that the cosmetics fit the mercenary in question?
the first question is not only limited to paints since
if you have seen zesty's video, you can just pull this shit off on sniper, or how about pyro and heavy?



but even if you don't want to acknowledge these absurd (and all of them are doable without quickswitch exploits!) exceptions, the second question is if you can recognize
who these characters are?



answer is a big fat no unless you already know which parts of the body you should look for (grenades on soldier, gloves on pyro, hat and glove on sniper), since it's also a simple case of the faces (and gas masks) making the merc themselves, cover that and you take a fuckton of character from them (and this ignores the fact that several of these cosmetics revolutionize the apparel of the classes themselves).
and for the third question, best summarized with these two demo sets


first example can be defined as fitting to the artstyle since it fits demo, he's scottish and he fights with proper scottish wear, second example is just demo with pajamas.
if you want a complete list of every cosmetic that can shit on the artstyle with an explanation towards it then refer to
zesty's ongoing class cosmetic review series.
I would also argue that the artstyle was fucked the second paint got added to the game because nothing ruins the artstyle of tf2 more than seeing hot pink or neon green in a loadout since both of those colors are not used in tf2 besides paint
that's arguable since the issue is not that paint got added in, but the classic issue of cosmetic creators being so retarded they make gargantuan paint regions and fuck everything up with the gameplay, i don't think i need to cover this part.
e:
actually fuck all formalities, i could've simply made this entire wall by just making clear that i REALLY don't like being reminded of a very specific and painful period in my life in a game where i'm supposed to forget about the pains of my life, i don't care if it's the super-duper irrelevant and easy to ignore exception, just the fact that THIS

absolute blight of a cosmetic has been conjured from the hands of some worthless tranny nigger faggot that needed his daily dose of drugs to forget about how much of a worthless piece of nigger gorilla faggot shit he (no women make cosmetics) is, and got implemented by one of the two valve-approved trannies in this game, is already enough of an argument to make about how you're a retard that willingly ignores the blatant humiliation ritual anyone with a brain is going through with these cosmetics being put in the game, if you don't give a shit just be upfront with it and don't tell people to not get pissy at this shit, this IS worth getting pissy at, and it's absolutely worth cursing every single second that all of this garbage is allowed in and it makes money to these """"people"""".