That’s not a “problem” with anti-cheat, it’s the entire point. It is a group of people who have chosen to give up their freedom to modify their games in exchange for the ability to play with other people who agree to the same.

It is okay for private clubs to have rules for the conduct of their consenting members.

FOSS is great for allowing individual freedom of software developers. It doesn’t provide functional solutions for all of the worlds problems, though.