It is essentially, chat logs and shared files. With filters for things like I said it in a thread with person X, on this date, and it had a link etc. That with a quick and easy UI.

I don't think there's anything stopping someone implementing a powerful search like that over IRC logs, or matrix logs or whatever. Just that slack were the ones who did it, and marketed it well so it took off.

Saying that, if I was launching a project or startup I probably would not choose to use slack.