[airstrike]

Lyft is arguably solving a much harder problem than essentially IRC

[dymk]

Slack is way more than IRC. Literally dozens of nontrivial features more.

[gkoberger]

You could also say "Slack is arguably solving a much harder problem than essentially a taxi company"

Both are solving really tough problems involving a lot of users and a lot of data.

[underyx]

Slack to IRC is what a library is to a bulletin board.