[kazinator]

The Internet solved this very nicely more than thirty years ago with a protocol called NNTP connecting article servers to form a network called Usenet.

The traffic is pretty low on Usenet these days. You can blame your aforementioned fragmentation for that. People would rather write to walled gardens. The idea of using special client to connect a server is somewhat alien to the generation that equates the Internet with the Web. There is also a learning curve to Usenet. For instance, newbies will be dismayed by a long delay while the client downloads the the entire list of newsgroups when connecting for the first time. This is something you can turn off. E.g. in the SLRN newsreader's .slrnrc file:

  set read_active 0       % don't download active file
  set check_new_groups 0  % don't bother me with new groups

I'm currently subscribe to these:

  comp.compilers
  comp.lang.awk
  comp.lang.lisp
  comp.programming
  comp.programming.threads
  comp.std.c
  comp.terminals
  comp.theory
  comp.unix.admin
  comp.unix.programmer
  comp.unix.shell
  sci.electronics.basics
  sci.electronics.design
  sci.electronics.repair

[jean_claude]

  > The idea of using special client to connect a server is somewhat alien to the generation that equates the Internet with the Web.

I think the problem wouldn't so much be needing a special client (app) to access a server (walled garden) as having to discover the existence of USENET, select a client, set up the client to point to their ISP's NNTP server (do ISPs even have NNTP servers these days?) or a premium or free 3rd party server, and then find an appropriate newsgroup(s) to follow.

Walled gardens also have the attraction of having a more user-friendly experience that can work across a variety of devices. The last time I was even moderately active on USENET, I was slurping newsgroups via a scheduled job running Souper and reading/writing posts on Yarn, a console mode program for OS/2. I'm fairly sure SLRN is console mode as well... not really a selling point on today's technology, where many people would be using their phone/tablet.

[charlesism]

In its heyday Usenet worked fairly well. The major advantage of a site like SO, is that it tends to have less repetition. The same questions on Usenet came up over and over again. On SO, the memory hole is smaller.

[speeder]

When I tried to poke around, what I found is lots of expensive clients and no obvious gratuitous alternative, except for some time, Google groups

[mirimir]

I believe that just about all newsgroups, except the binary ones, are available via Google Groups. Many years ago, Google bought archives going back to more or less the beginning.

Thunderbird is an OK news client.

[DanBC]

tin, slrn, or pan are good free clients.

http://tin.org/

http://www.slrn.org/

http://pan.rebelbase.com/