Email, Usenet and IRC was great.
Email, however, went dogshit due to spam. From simply having the office mail-server, everyone went to Gmail and Office, who didn't always want to accept legitimate email. Thus, encouraging more folks to move to it.
Now we're in a situation where everyone is "forced" to use crappy interfaces, email is htmlified shit, and more and more companies require you to use the official client. Which in the case of Office365 means a very, very crappy web solution if you're on for example Linux. IMAP is often simply turned off due to whomever decides security has decided that's a bad idea.
Mailing lists used to be great. But got broken in a variety of ways due to spam filtering among other things.
Usenet was great once upon a time, with internal newsgroups etc. That died too.
IRC was, and is, an excellent way of having instant messaging. Unfortunately it wasn't business friendly enough so only the geeks used it. It was a great way to coordinate, though.