Yeah - in the terminology here it would be more like a whole group of communities (since we call each "topic" on an instance a community) but yes.
Admins can (and do) also block individual communities on an instance that is still federated, such as lemmy.world blocking !piracy@lemmy.dbzer0.com but leaving most of the rest of dbzer0 connected.
My favorite thing about this is the context: It was literally about losing a video game.(Data thought he was broken 'cus he lost)