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