There's still room for improvement, but Linux gaming has come a long way in a short time.
I remember when Proton launched it was like magic playing games like Doom and Nier Automata straight from the Linux Steam client with excellent performance. I do not miss the days of having the Windows version of Steam installed separately.
Congratulations, you played the only Windows game that consistently scored Platinum rankings on Wine's AppDB in the mid to late 2000's.
If you went past the tedious install process and didn't mind the lack of Vsync on OpenGL, WoW ran like a dream on Linux and could actually pull higher framerates than on Windows.
Valve definitely deserve credit. No other games publisher has contributed as much to the Linux gaming community as them, and they did it because they perceived Microsoft as an existential threat to their storefront.