IRC is part of it. The protocol is a bit dated if you discount the IRC v3.x proposals but the core feature set is good enough. Today's chat darling is Slack, and it struggles on groups with a couple of thousand people no matter what they do. IRCd was running individual servers with tens of thousands and networks with 100k+ in rooms with thousands on hardware less powerful than a modern smartwatch. The problem with IRC is that mobile clients universally suck, the web interfaces suck, and most desktop clients suck too. You could support all of Slacks features apart from video/desktop sharing with improved IRC clients but nobody bothered to write them. Instead we got a JSON/HTTP nightmare that needs 100x more hardware than it should, that has weekly downtime, and regular client crashes. But hey, they're valued at like 2 billion so they must have done something right.
I was thinking more about forums though: mailing lists and usenet are the prelude to the modern web forum. Everything that sucks about this forum is fixed in those:
- Search sucks: local client indexing means you can throw ungodly complex queries without bogging down anybody but yourself. The indexing system behind notmuch will easily handle a forum this size as well as a forum with a couple dozen posts.
- Spam filtering sucks. Email systems already have spam filters that are damn good that can operate at the server level (see spamassassin et al) and then further local filtering can be done by users (e.g. to filter out 'political threads' or whatever they dislike
- notifications of topics, mentions, messages from friends, quotes, etc. are handled trivially with postfix at the server level or locally via something like notmuch tagging
- Overhead: to load this page takes > 400 http connections and more than a megabyte of data. As email, it'd be a few kilobytes, available to read offline with syncing between all your devices automatically.
- Composition features: you can use your favourite editor to compose messages. You get threading, forking, quoting, merging, references, etc. You can have arbitrary attachments or none at all. You can read content with your favourite pager, you can have secure/private messaging between people, etc.
- Privacy concerns don't have to exist: I supply my own client, my own mail server, and everything is opt-in form there.
- You leverage the notification system I've already set up: maybe I only want alerts here between 6pm and midnight, or any time on weekends. I've already configure my phone/laptop/desktop for that - nothing new is needed.
Outside of ultra-nerds writing software you pretty much never see mailing lists any more.
Don't get me wrong: there's a lot we could do to improve email and irc, but it seems to me like everything we've done by ignoring them has been worse. Maybe this is just another case of "People who don't understand UNIX are doomed to reimplement it poorly."