You picked the server you joined but the benefit of this over something like Lemmy is that you don't get the split community/discoverability issues that impact the average user as everyone was reading and posting to the same newsgroups but from their chosen NNTP server.
Let's have something like NNTP implemented in ActivityPub (is this possible? I'm not familiar enough...) where the news servers are decentralised and users pick whatever one they want but the newsgroups themselves are the same across all the servers.