Containment boards always seemed like a good concept to me.
I saw it as a way to keep the main community clean by providing some form of... "venting" if you will. The whole reason /s4s/ on 4chan still exists is because it keeps the main boards free of stuffposters but still having a set list of global rules that still apply, even while being less stringent on them. I'm not saying that the AoT boards should be this way, but there should definitely be a board where users can-
take massive stuffs of autism and smear it across the walls.
So like global rules like no research, and trap links would still be bannable but spamming wouldn't be one for example.