It's been a while since anything failed on Proton. I can't really see why anyone would jump through the hoops to run Windows on this thing.

Proton has become astonishingly good.

Even niche titles either work, or at worst I need to use a specific build of Proton (usually Proton GE for some obscure video formats).

I also have had good luck using Bottles to run Battle.net for Diablo 3 and 4.

I don't play many competitive multiplayer games though, where very aggressive anti-cheat can be a problem.

The primary games that don't work (yet) are Genshin Impact and Honkai Star Rail, both by HoYo. There's some particular quirk of their anti-cheat that causes the games to crash instantly. That said, it's worth noting that occasionally Genshin Impact has worked for a few weeks, so HoYo seems to be testing a change that might allow it to work consistently eventually.