Exactly. Back in 2012 or so I wrote a web chat system that had all that (minus the screenshare & voice chat) and it was quite a challenge supporting all the permutations of links, images, emoji's, bbcode, etc. It's a pos in today's standards but back before slack it was "on the right track". Slack pretty much came out of nowhere and killed the effort though. To your point about a bouncer, I think a lot of folks are nostalgic and forget what a shitty system IRC was. Net-splits, bouncers, no filters or mod tools other than kick. No embedded media unless your client did magic. It was some folks' first foray into online community so naturally they want that feeling back.

I'm glad to see this pushback against centralized monopolies. The open-web needs more openness.