@sugar_in_your_tea Private servers exclude MMOs as a class of game. That works well for death-match style (or BG3 style) 4-player games, but doesn't work for 30-300-3000 people games.
Anti-cheat server-only allows too many cheats. There's already enough trouble distinguishing someone using wall-hacks from someone with good headphones in a game that does 3d-spacial-sound... trying to do that on the server side ... just won't work. Same applies for other ways of increasing the costs if detected