Irc with proper roaming support and push notifications would blow discord or slack out of the water.
Newer is not necessarily better.
Newer is not necessarily better.
"this service is only usable on your phone if you also sign up for another service" pretty much makes it a non-starter.
IRC has had literal decades to be improved and only now do people get serious about it after Slack and friends sucked all the oxygen out of the room.
Older isn’t necessarily better either. IRC has stagnated hard, about the only thing it has on the competitors is that it’s free.
It's more than 'free'. It's an open standard. You can write a slack client in your favorite language and it will continue to work for years.
Slack does not compete with that.
And doesn't require 8 GB of RAM to run a client.