“They forked Wine and started to add an insane amount of patches to make games work on Linux, no matter if they didn’t have a Linux build.”
Proton did more for Linux gaming in four years than two decades of Winetricks and PlayOnLinux. It wasn’t charity. Valve wanted a hedge against Microsoft owning the PC storefront, and the Steam Deck is that hedge. Linux users still win, because for once a company’s self-interest points their way.