Don’t they already have extensive block lists that you can “subscribe” to? I think some official blue sky account was added to some and they got super mad?
That's an additional (but closely related) issue. AFAIK those lists work at the user level to filter what you see, so while they aren't a network breaking "guilt by association" practice they're a form of centralized, lazy, delegated moderation that has outsized impacts on any borderline cases or false positives.
Besides those appview block lists, relays also block stuff. I know relays block stuff because bluesky isn't being sued for distributing child pornography, as it would be if it didn't block stuff.