Windows gaming is way, WAY bigger than Steam!
For example, I recently went and played some World of Warcraft for old times sake with some friends on Linux. All I had to do was open Lutris which is available through a Flatpak on the SteamOS discovery tool, and then from Lutris you install the Blizzard Launcher. Opening the Blizzard launcher lets one install and play any of their games.
I was able to play Overwatch on an AMD ubuntu laptop flawlessly.
Unclear if parent is referring to "Gaming" as a whole or just including boring capitalism numbers like "marketshare" etc.
The rest have kernel level anticheat, unfortunately.