In the past I keep them separated but manage them, especially store&search with full-post locally saved in case it disappear from their origin it was hard or ineffective.
Actual trend is suppress anything free and not fully controllable: usenet is decentralized and no one can really own it so it's pushed as much as possible to the oblivion, offering colorful and limited substitute from StackExchange to Reddit passing through HN and /., same for mail, they are not distributed but still decentralized enough to be out of complete control, so here came webmails just to avoid people keep their messages locally and paving the way to new "email substitute" that are web-only, fully centralized etc, Slack, Google wave etc are all tentative to bury emails in the past. Webcrap is the same, instead of a WWW of hypertexts. Push of mobile instead of PCs is the same.
Also with these kind of "modern" solution we as clients can't really discuss, try HN, try Disqus we do not really have control and voice, we are only data producer to be milked.
There are fewer, but not exactly "very, very few": http://top1000.anthologeek.net/
Because Usenet is fully distributed, the high number of site-local servers in the past was in large part about reducing bandwidth costs (having a Usenet server on your network is a lot like having a caching proxy, but even more effective).
Running your own text groups Usenet server has also never been cheaper. Most small Usenet server operators will be happy to peer with you, as long as you have a static IP.
The market for binary newsgroup providers is also healthy, but that is not about discussions anymore.
- I can follow many site I like, instead of using an aggregator I do not own nor control;
- I can read posts/articles/listen podcasts without crappy webui full of advertisements;
- I can KEEP posts I'm interest in as long as I want, offline, indexed, tagged in my personal maildir taxonomy;
I still have to find an alternative for that. Usenet of course was a far better way to follow news, ask questions etc, but unfortunately people do not know it anymore... Any modern "feed reader"/"podcatcher" I found, except elfeed are crappy, buggy, unuseful ridiculous apps that try to mimic aggregators instead of focusing on contents.