That was the fun thing about Usenet back then - lots of open exchange between key people and anyone could join in (which eventually was its undoing).
Usenet started as a relatively low-volume medium connecting ivory towers. It became huge with the opening of the Internet to the public, with ISPs everywhere hosting NNTP servers.
Usenet ended up being used for massive file sharing, which was probably a big reason for ISPs, in turn, dropping NNTP servers. They didn't want the administrative overhead of providing all that storage, and plus most of the content was copyright infringing.
So, Usenet is just back to the way it was in some ways. You will find some people that qualify as key people in the comp newsgroups.
The original key people from the 1980's or 1990's aren't coming back; they are deceased or retired.
By the way, the same person, John Levine, has been moderating comp.compilers for well over thirty years, since January 1986. Someone will have to pick that up sooner or later.
Another factor was that maintaining a news server was a PITA for the ISPs.
Binary groups were a separate thing. What killed USENET were spammers and trolls; the protocol was conceived in an era of gentlemanship and collaboration and had no antibodies against the wave of bozos that would come later.
Eternal September.
No. It wasn't a problem to run an NNTP server with no binaries, and many ISPs did so. (Source: I ran a large NNTP server for a number of years)
The undoing of USENET was people, quite simply. The deluge of stupidity and spam was what chased away the smarter people, which in turn made the whole thing less valuable.
I think that is a great pity. These days it's much more difficult to find niche forums and talk to other people that are interested in the same thing that you are into. And then you have to "sign up" and deal with the catastrophically bad forum software. It's a big step back and I wonder if we'll ever be able to recover.
Technically Reddit fills up those shoes pretty nicely
Eternal September
Chanels, depending on what you're looking for, but there used to be a lot of them, just look number of users.
In practice Discord seems to be where everyone is nowadays and while Discord is little more than a proprietary IRC with built-in history and images, people are active there. It basically feels the same as when i used mIRC back in the 90s and early 2000s - including the part where some channels/servers were so full of people i could barely keep up. If anything it is more than i ever saw on IRC as i am in 25 "servers"[0] with various channels in each (though like with IRC i only participate in a handful of them and i only occasionally browse the rest).
Fortunately Discord works via the web and i have the web interface pinned on Firefox all the time so i don't have to use their client.
[0] i really dislike the name as they aren't really servers, just groups of channels - everything is on Discord's proprietary server
https://news.ycombinator.com/item?id=9987679#:~:text=The%20r....