There was no "main" source of truth for each version and each ISP could have its own set of posts. The bofh.* hierarchy for example had a very limited distribution and if it was found that one of the sites that provided it was leaking it to the general public they'd collectively cut off sites from being able to post or receive posts until they rectify their configuration.
Sure, an ISP could host its own news.answers site and not accept posts from others for that group nor pass messages from it out to others... but that would be a rather lonely place.
Likewise, one ISP may have a different set of posts that it shows for a news group because of moderation actions (we don't accept any posts greater than 1MB in size because of disk space issues and we don't host any newsgroup named *.binaries).
Federation comes from exchanging those posts using a common protocol - NNTP.
http://usenet.trigofacile.com/hierarchies/index.py?status=pr... and https://web.archive.org/web/20220815151921/http://bofh.taron...
Sure, an ISP could host its own news.answers site and not accept posts from others for that group nor pass messages from it out to others... but that would be a rather lonely place.
Likewise, one ISP may have a different set of posts that it shows for a news group because of moderation actions (we don't accept any posts greater than 1MB in size because of disk space issues and we don't host any newsgroup named *.binaries).
Federation comes from exchanging those posts using a common protocol - NNTP.