Banning piracy? Like the mere encouragement or?
Just the mere encouragement & discussion, yes. The banned communities do not allow direct links to pirated content (!piracy@lemmy.dbzer0.com has a rule forbidding that).
It's strange to see people saying there was some sort of legit reasoning, the lemmy.world admins did not receive any sort of legal DMCA/NTD request or anything of the sort. They were simply trolled hard by a brand new account from lemm.ee asking to defederate from "piracy" communities and lemmy.world admins took the bait. See the post yourself https://lemmy.world/post/3175920
Incidentally that same user has created troll accounts at other instances & have been getting themselves banned, they were already banned at the dbzer0 instance (see https://lemmy.dbzer0.com/comment/1956277) so it looks like it was simple retaliation to attempt to trick other instances into defederating/blocking them.
Tried it out a few years back, it sort of works okay for those looking for something like this. Its interesting feature is the ability to search among other clients running the same software so it's a sort of distributed search. To do that I think it has to advertise the torrents you've downloaded/loaded in the client so other people can find yours in the search.
The UI is a bit difficult to understand, takes a while to figure it out how to actually use it IMO. Probably a good idea to read the usage manual on their github page.