Fediverse

Because they're ancient, depreciated, and technically obsolete.

For example: usenet groups are essentially unmoderated, which allows spammers, trolls, and bad actors free reign to do what it is they do. This was not a design consideration when usenet was being developed, because the assumption was all the users would have a name, email, and traceable identity so if you acted like a stupid shit, everyone already knew exactly who you were, where you worked/went to school, and could apply actual real-world social pressure to you to stop being a stupid fuck.

This, of course, does not work anymore, and has basically been the primary driver of why usenet has just plain died as a discussion forum because you just can't have an unmoderated anything without it turning into the worst of 4chan, twitter, and insert-nazi-site-of-choice-here combined with a nonstop flood of spam and scams.

So it died, everyone moved on, and I don't think that there's really anyone who thinks the global usenet backbone is salvagable as a communications method.

HOWEVER, you can of course run your own NNTP server and limit access via local accounts and simply not take the big global feed. It's useful as a protocol, but then, at that point, why use NNTP over a forum software, or Lemmy (even if it's not federating), or whatever?