[avtar]

Mobile clients, persistent chat history when switching clients/devices, search, @mentions notify you when you're away from your desk, and easy integrations with lots of services.

P.S. I mainly use IRC everyday :)

[ant6n]

"persistent" up to 10,000 messages per team.

[zaphar]

Forever if you pay for it.

i.e. they have a revenue stream.

[pmlnr]

Which is IRC + ZNC + Andchat + bots...

[gisenberg]

This echoes the "couldn't you just replicate Dropbox with x + y + z ..." mindset of the past.

[drdaeman]

Why the past?

I tried to use Dropbox but it just didn't have what I wanted it to have. So, I find it to be not only replaceable, but awfully inferior to the x+y+z-style solutions.

[st3v3r]

Which takes time to set up, whereas it's already done for you in Slack.

[pmlnr]

Of course it does. But you get to keep your data for yourself.