[1] Case in point: glibc's compatibility guarantees are weaker than what you get on Windows. (For instance, your system's glibc cannot be older than what a game is built against, which may present problems for devs using Fedora/Arch and players on Debian/LTS Ubuntu, something I've experienced first-hand for my apps.) The X11 to Wayland migration is also still underway. (Though things are getting better, the attitudes of some Wayland maintainers are a bit concerning: "I don't [care] what you think is normal behavior for games. You get certain guarantees with wayland. Deal with it. If clients decide to do exactly what they do on windows or X11 they won't work correctly." [3] I'm not sure game developers would enjoy such reception.)
[2] https://store.steampowered.com/hwsurvey
[3] https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18...
I'd say win32/flatpak/libretro are the only sane way for games to target linux right now. The fact that linux doesn't have real "runtime" and major components required by games link against libc is what makes linux really unstable for anything that needs to open window, draw stuff using GPU and play audio. It's possible to create static binaries for linux that work for eternity, thanks to kernel being actually stable. But link against something in /usr/lib and it all goes to hell. If the GPU drivers and libs that provided basic window / audio did not depend on libc and were standalone, the situation would be much better. Here's good video about this problem space btw https://www.youtube.com/watch?v=pq1XqP4-qOo