Cheaters don't want to play against other cheaters. If they end up against only cheaters that's a kind of soft-ban or shadow-ban and once they figure out that's the case they'll do the same steps as if you had actually banned them. It also angers legitimate players to know that the top ladder tier is for cheaters only. If you're 200th in the world and legitimate, other players will say you only got that rank through cheating.

And the very best cheaters are still good at the games they cheat in, they just want to use cheats to be even better. One famous example in a game I play is Riolu in Trackmania. He was probably one of the top 10 players in the world. But he wanted to be #1. When he was accused of cheating it took a mountain of evidence for anyone to believe the accusations because he could set a world record live in-person. He just used cheats to be able to do it with fewer attempts.