YMMV
If you have an old nvidia card, you're going to have issues with some games. BF4 for example, no matter what you do you will have lag and stutter
There's wayland and lack of support for nvidia cards, and major distros and GUI's dropping x11 in favour of wayland (regardless of whose fault it is or if it's good or bad in grand scheme of things, whoever has an nvidia GPU is going to be forced to use other distros or windows)
And then the whole proton and wine stuff... I just installed CoD 2 and had to fetch some commands in order for it to run, else it crashed after playing the first cut scene. And then there are other games, like Divinity dragon commander, that I couldn't figure how to get it to run. Tried several proton versions, none of them launched the game. My fault or ignorance? Perhaps, but on windows it would run first try.
1 - YMMV, as I mentioned
2- as a consequence, popular distros like Ubuntu and Fedora too. I expect other GUI's and therefore distros to follow
3- Didn't mean to imply they don't, what I meant is that they have issues and will make users jump to other ships.
4, 5 and 6, Lutris and later Steam itself when I was running out of ideas, and yes it does run on Linux as long you can figure out the correct proton/wine version or buy the game from Steam. Point here was that gaming on Linux can be convenient or very annoying, depending on the games you want to play. YMMV