Even if it's not, performance gap is not significant to use Windows. Gaming on Linux never has been better.
Being able to get a respectable gaming experience will for many be the reason that they can stay in the OS that they prefer for other reasons.
While playing games developed and sold for Android/NDK or developed and sold for GNU/Linux isn't really a thing.
Proton will never stop being a requirement for the large ecosystem of Valve's gaming library.
Apparently the lessons from OS/2 weren't learned in due time.
Using APIs for lock-in is an old anti-competitive trick, so it's fun to see it failing for gaming.
A Phyrric victory if there was one.
Now had they managed to convince said studios to write native GNU/Linux games, or to port their Android/NDK games into GNU/Linux, I would have agreed Valve managed something.