Anti-cheat is still a major issue on multiplayer games that are not PVP-centric, like MMOs. In these cases, the negative externalities of cheating are more like a tragedy of commons than griefing. Cheaters and bots screw up the economy and increase competition for training / farming areas, but generally only in aggregate. Much easier to justify than directly ruining someones experience by killing them instantly every time they spawn.

This extends even as far as Chinese dress-up MMOs like Love Nikki where people will use bots to vote randomly in competitions because there are substantial rewards for mass voting. This means that people are directly injecting randomness into one of the core parts of the game, but the players who do it feel it's justified because it's a pain to get those rewards otherwise.