Comment by Avamander
Funny thing is, I still use it.
It might be _the_ fastest chat platform right now. Other things like Whatsapp, Messenger, Telegram, Signal, Matrix/Element, Discord, Slack, Rocket Chat, Mattermost (and all the platforms that implement some kind of a chat by now), are all significantly slower. Sending messages takes longer, UI is slower, everything is slower somehow. The only exception that I know of being IRC.
It also allowed tree-shaped groups, you can nest as many as you like depending on your needs. It's so handy compared to the limited server/channel/thread logic elsewhere.
I will miss it dearly once they shut it down.