Maybe it's worse on ML instances. I honestly would start explaining it by looking at how much red-scare crap they go through.
But generally, I think you're right ... I've seen ban-happy mods too, and not on ML instances.
I'd say it's people learning how to manage decentralisation/federation. It gives people a greater sense of ownership and power and so you get some power tripping and a new source of drama and identity politics (based on instances). Kinda sad actually.
