> so much so that even open source projects use it over IRC.

Remove the small amount of technical know how to "properly" use IRC and make chats (and permissions) persistent, and I imagine you'd end up with something that looks eerily like Slack.

That said, I think the Slack load-time in-browser is silly-long and I get spammed with notifications. As for threads, Zulip (https://github.com/zulip/zulip) does things "right" and I wish Slack would rip off their approach (central topic is the "room" and threads are independent, visually-separate-when-highlighted chats within a central topic).