in the 90s, there was microsoft messenger. real time, point to point (and maybe ptmp) chat, audio, and video. What replaced it? I have to run a coturn (STUN) server just to be able to talk to my friend in a private way, which means now i gotta deal with some provider for hosting both coturn and, say, Matrix (Synapse).
I also run a PBX, just in case coturn decides to stop working from lack of use. Now i gotta make sure i start the PBX app (3cx) once a week otherwise android helpfully removes notifications for me!
AIM, ICQ, etc were great - and i'm discounting "presence", because that was a small part of it. realtime communication for "free". I've been running chat servers for over a decade, and right now, there's three people on my matrix server, me, wife, and my best friend. there's five people on my PBX, same three plus my youngest child without a SIM card, and grandma, so grandma can call kid and vice versa. I've run ircd, matrix, rocket.chat, mattermost, a couple of the jabber systems, ventrilo, teamspeak, hand-rolled garbage.
we've had people sign up and chat once, but as soon as notifications stop working we never see them again. Heck, i have 3 PUSH accounts just to make sure that notifications go through everywhere.
Meanwhile, 20-25 years ago, load up trillian or AIM/ICQ and there was everyone, literally everyone. I know facebook ate that lunch, but i refuse to have any facebook apps on my phone, and most people i know refuse as well, so that's a non-starter. Texting is still spotty, because VoWiFi tends to just magically stop working if you leave the wifi area a couple times in a day, so texts will sit in limbo until you realize. Phone calls are the same way (except via PBX, those always seem to work for some reason...)
running out of IPv4 and the ubiquitousness of CGNAT have killed what the internet was. And that's sad; "nostalgia" isn't necessarily a negative thing. It used to be better, at least in the West. Maybe wechat and signal and telegram and whatever work better for the rest of the world now than any of our stuff from 25 years ago, i wouldn't know, because i know exactly zero people on any of those services - i've checked, once every couple of years.