I’ve been doing it for 5 years and posted about it 3½ years ago:
And actually raytracing works now, too.
In that thread I mention that you won’t be able to tell the difference between it and a native client, and that’s… not quite true right now, but close.
Sometimes you have to fiddle with wine/Proton because the battle.net launcher update doesn’t play well with the new version. This never happens to WoW itself, just battle.net, but still. It happens often enough that it’s annoying. I don’t know why - Blizzard must be doing some insane technical mumbojumbo in that cosebase. It seems like it is agent.exe that explodes, which is hardly unusual. That thing sucks on macOS, too.
I also think they can deliver a better game on Linux if they go native. Maybe they won’t get too much on the graphics API side, but they will get the ability keybind the with the windows key as a modifier, and they’ll get something that’s much easier to support - a stable API with no translation layers! And the game should also run faster because it doesn’t need to translate method calls from Windows style to UNIX style.