The UI was a trivial enough component that it can be replicated by a dozen competitors, to suddenly become a hugely busy space such as it is now. Those people

The UI was a trivial enough component that it can be replicated by a dozen competitors, to suddenly become a hugely busy space such as it is now. Those people with money can easily be stolen out from under Slack, precisely because they didn't innovate, they simplified. Slack is "just IRC", and the proof is that if it were more, there wouldn't be nearly as much competition in the space, with more people joining every month, it seems.