I don't think anyone is saying "DIY matchmaking", they're saying "community servers" - and everyone in any given community knows everyone else, ideally IRL, and any newcomers are going to be watched, both for their technical performance but also their social performance.

Cheating among your friends has the ultimate death penalty of losing those friendships. Most people don't want that.

This is why most cheating is not among close friends, but where there's an open buffet for the energy vampires; anodyne corporate "matchmaking" where the game corporation will place you with other customers of the game corporation at its choice. The cheater does not have to face a panel of their peers, they only have to slip past the inattentive corporation to be placed in a server with delicious innocent strangers who they will never see again once they've had their fun.