This isn't about stopping cheaters (cheat detection). This is about stopping repeat cheaters trying to ban evade. Detecting cheats, especially nowadays with hardware cheats (DMA, etc), is an entirely different ballgame.
IMHO, one of the most effective way to stop ban evaders is to actually charge money for the game.
IMHO, one of the most effective way to stop ban evaders is to actually charge money for the game.