But what kind of cheats? Aimbotting and seeing through walls don't apply to VR chat. And no matter how modded your client was, you couldn't spam endless grenades in Counter Strike - the server knows how many grenades you have, and where you can throw them.
Due to starcraft 2's design, defogging hacks were plentiful.
Anyone who has played TF2 for a significant amount of time has run into hackers landing impossible shots, e.g. through walls
before EAC, there has been VAC (along with two separate community-ran anti-cheat services for source games), Battleye, Warden, etc. It seems universal amongst those involved, that client-side anti cheat helps way more than you expect.