While you’re not completely incorrect about it not being Linux’s fault, trying to gatekeep “anywhere outside of Steam support” is just as unhelpful as game developers not focusing on Linux.
Does that same logic extend to not-Steam’s ProtonDB, a 3rd party website for tracking how well games play on Linux using Proton?
Alphabet’s monopoly is bad, make no mistake.
But they aren’t controlling all electronic means of communication for 90% of the continental United States, as AT&T did in the ma’ bell and pa’ bell days.