I think Nostr is more similar to irc than to usenet.
In usenet you could have newsgroup like in RSS.
Discussion
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RSS is for subscriptions (read only).
Usenet was for news/forums, like mailing lists but with its own protocol (NNTP), and it was great.
But with today's Internet size it wouldn't be manageable, since it's very much a directory/DNS like structure, so very centralized.
As for the original question, I still don't know much about NOSTR as a protocol to differentiate it from NNTP, both uses relays to distribute messages. Maybe there are similarities.