Anti-cheat is allowed. There are a handful of anti-cheat systems that can’t work on Linux, but IIRC, they are in the minority.
They are the minority, but have large player bases. Eliminating that barrier would mean that Linux devices (not just desktops) would be a one-shot win for most consumers.
Which is why it won’t ever happen (anti cheat allowed). Microsoft makes sure of that with $$$ to those devs that refuse to support Linux.