I think there's a reasonable argument that the most stable Linux gaming API surface is actually Proton.
None of this is really going to change until we end up with a situation like the EA/Apple Store conflict: a major player unable to sell a game on Windows for some reason.
Also, it's something of a pragmatic choice -- Valve did put major effort into native Linux games around 2013, but the effort fell flat for a number of reasons.
Proton is them trying a different path towards severing or lessening the Windows dependence, in my opinion.
That is like saying the most valuable gaming API is Dolphi, MAME, or LinUAE.
Almost certainly more people playing 80s and 90s games through emulation than on original hardware, so .. yes?
Except the main reason is because 80s and 90s hardware is dead, or hard to come by and repair.