USENET, was in my opinion, one of the best features/protocol of the initial internet. I loved USENET ever since I discovered it (91/92) and I still use today a news reader through gmane, looking down at forums (just like this one) like a sad evolution.

Having an USENET server provided by your ISP used to be a standard part of the package. They would probably not carry alt.bin, but in the end it didn't matter.

A truly P2P, open, messaging network, of the likes that you'll never see developed again due to commercial exploitation. USENET had "flaws", but honestly they're minor.

The store and forward protocol required quite some disk space at the time. This resulted in several nodes to drop bin/alt.bin from the network (which in my opinion was always a hack providing nothing really useful, with yencoding/par and the like). But by today standards, you could probably run a node carrying the entire network with just maybe a bit more than regular consumer hardware, since it's just text in the end, and the server is very simple: I used to run one server locally just for me.

How big a today's network could be?
See for yourself: http://gmane.org/stats.php
Or: not big for any ISP to carry in full with just one sysadmin.

The network relied on "control" messages to create/delete groups automatically (as opposed to manual subscription), which due to the lack of authentication/encryption in the protocol, were very easy to spoof. A gpg-signing mechanism was later put into place, so that nodes peering with each other could establish a chain of trust by themselves. This was pretty nice in retrospect (and awesome by today standards), but the main problem is that creating new groups was a slow and painful approval-based process: people often wanted small groups just for themselves, and mailing lists offered the "same" without any approval required.

Having a large open network started to become a big attractor for SPAM, and managing SPAM in a P2P network without authentication is a harder problem to solve than a locally managed mailing list. For the same reason, trolls could be a nuisance at time.

Some people claim that USENET became 1) too big 2) a receptacle for copyright infringement. Both claims are bullshit: by excluding binary groups (which was ubiquitous by 91/92 when I joined already), the network started in a consistent volume decline already in the late 90ies, so it cannot be that hosting a node in 1998 became impossible in 2005.

Here's what happened: running a local server became so easy and cheap, that running mailing list offered local control and almost zero overhead. People that had niche groups started to create mailing lists with open access, and people migrated in flock. Why share your discussions in comp.programming.functional where you could create a mailing list just for your new fancy language? (it's pretty sad, because I loved the breadth of the discussions).

Discussions on general groups became less frequent as most of the interesting ones were on dedicated mailing lists. The trend worsened significantly as forums started to appear, which lowered the barrier to entry to people that didn't know how to use a mail client properly.

The sad truth is that now most of the general discussions aren't openly shared anymore, and happen either on local websites (like this) or local mailing lists.

I've been using gmane.org to subscribe all open-access lists that I ever participated into. Most of the time, the list I'm looking for is already there.

In a certain sense, gmane.org offers the best of NNTP with the best of mailing lists: you can create your own lists without approval processes, and you can read any other list without having 1) to subscribe directly 2) having to store messages locally 3) see instantly the archive [as far as retention goes]. The mailing list administrator has still ultimate veto on what goes on the list, so that local authority is never undermined. On the other hand, NNTP clients are built to read massive volumes of messages, that would make reading reddit a breeze.

What gmane.org lacks though is the peering. One of the central NNTP features of the time was definitely killed.