This is simply not true. As someone who has been gaming exclusively on Linux for over a decade I don't even bother checking for support before getting new games anymore because almost all of them just work with Wine/Proton or only need minor workarounds.
The only things that do give problems (besides new releases which are promply fixes) are some multiplayer games with anti-cheat that intentionally breaks under Linux. But if you support those kinds of games then you reap what you sow.
Proton is also not really magic - it's mostly just Wine + DXVK and while Valve has improved both they didn't start either of them and weren't involved before they became viable. SteamDick is entirely irrelevant here - if anything it has caused developers to not release native Linux builds because of the way Valve does certification (or unfounded fears on the devs side).
> If you want to be able to play any given computer game
Moving goalpoasts much? This is like saying you need to be an american in order to use computers because there are some computer models that were never exported. There are more games than you will ever be able to play which work under Linux, for any genre. For older games it is often even easier to get them to work under Wine/Proton compared to native Windows.