Is there a broader tutorial for this, newsgroups mostly missed me, I don't really grok how they fit into the greater internet or how their hosting works or why you have to pay a separate provider
As for "why pay separate provider" -- that would be because circa 2000 most ISP's dropped offering Usenet access for their customers as part of the deal, which created a market for the paid providers.
In the dark ages when internet access was limited and/or via dialup for most of us, there were several tools and protocols to work with what we had: email, ftp and usenet were some of the main ones. Usenet was basically a primordial set of distributed forums platform (and quasi-social network) where copies of the data were stored locally. It was how a lot of information got disseminated prior to the mid-90's when the web took off and then over.
IMO an analogy to modern times would be a federated Reddit. I'd liken it to Lemmy but don't have enough experience with it to be sure it doesn't ruin my analogy in some way :)
It's probably better, on a technical level, than any of the fediverse stuff. I understand that Usenet works as a gossip protocol with nodes sharing everything they have (and haven't filtered) while Fediverse usually relies on directly contacting the origin server over IP. The integration between different instances on Mastodon and Lemmy is nothing like Usenet. The integration in the Fediverse is limited to following users, liking posts and replying to posts on other servers, using your federated identity on your server.
Update: I actually used Usenet a bit yesterday, mostly reading administrators explaining how the system works, and deleting spam. It's a cool system, I guess.
It should be possible to have other things built on top of the protocol. The protocol is a store-and-forward broadcast system, and is mostly agnostic to what goes in the packets, although if you want to add a group, each server operator has to agree to carry it, and they can have server-specific restrictions on things like message sizes, dropping messages outside the limits, so it isn't reliable. If you wanted to make a Usenet group simulating Reddit, you could easily pass votes through the system. Clients would have to interpret them, so you'd have to write your own client.
It's tolerant of spam as long as it isn't extremely excessive. There was talk of de-peering Google due to a large volume of spam, before Google made the decision itself, but most groups are about half spam besides that. The low volume of actual users contributes to this.
There's a group, I think news.admin.peering, for requesting your own server to be connected to the network. I see many successful requests from various people in the group's history. The network is fully decentralized, so being connected is reliant on at least one other person being willing to connect to you.
There was a period of time where the notion that everything would be archived was unfathomable to the average user. Sure, in theory it could be. But storage was expensive and the value of storing that stuff was low.
Unfortunately, when DejaNews came out it became clear that at least one person out there recorded everything. Many an embarrassing post of mine was unearthed. When one has tens of thousands of posts and is young & stupid, that was bound to happen. Of course now all these years later I can barely find any of my posts on the internet, embarrassing or otherwise.
>I don't really grok how they fit into the greater internet or how their hosting works or why you have to pay a separate provider
In much the same way that you need a specialized email client to use IMAP/SMTP, you need a specialized client that speaks NNTP to access usenet.
The providers are heterogeneous but usually are basically beefy servers connected to fat pipes to handle the massive volume of traffic, which is why you typically need to pay for access.
One way to think usenet/newsgroups is as a set of distributed peer-to-peer mailing lists.
You post a message to your (NNTP) server. Your server connects to other peer NNTP servers to transfer messages back and forth, so eventually your message will propagate throughout the usenet network. (40 years ago peering was through UUCP, etc, and done at night when phone calls were cheaper or only to other local numbers so it might take a week, now it doesn't take that long. See also, bang paths).
