User reports are indeed a common tranche of anti-cheat systems.
But in chess terms "Middling player occasionally made suspiciously good moves" is a pretty weak cheat report. But if you can tell they had stockfish running and changed windows to it several times in the course of the game? Well, now you've got a very clear cheat report.
More broadly, many gamers are chasing the dopamine rush of winning, complete with slot-machine-style flashing lights, music and dancing character animations. Being awarded a win by e-mail a day or two later doesn't really compare.
But in chess terms "Middling player occasionally made suspiciously good moves" is a pretty weak cheat report. But if you can tell they had stockfish running and changed windows to it several times in the course of the game? Well, now you've got a very clear cheat report.
More broadly, many gamers are chasing the dopamine rush of winning, complete with slot-machine-style flashing lights, music and dancing character animations. Being awarded a win by e-mail a day or two later doesn't really compare.