You can't prevent client-side cheating with a server-side implementation. For instance, making enemies on the other side of a wall visible uses data that the server has to supply to the client in order for the game to work, just in an unintended way. The server also has no way to verify whether the client is accurately conveying the results of user inputs or gently correcting them to move the aim to an enemy's head instead of a gazebo.

It would still be nice if all game companies supported Linux, but it requires active effort and isn't something they can get for free by being better programmers.