Neat story, but I don't see the analogy. OP says he/she doesn't see any innovation, not "this innovation is obvious". At least tell us an egg or two that Slack cleverly stands on end.
Now it occurs to me I may have been making a distinction (about the nature of innovation) where there arguably isn't one. Still, I think it's fair to ask exactly what Slack is doing right. If there is a real innovation, someone should be able to tell us (there've been some good responses); otherwise it's just lucky network effects or a fad.
