I find it funny that HN can criticize Slack for sticking to their main product without adding new collaboration features, while criticizing Dropbox for doing exactly the opposite.
I'm not very familiar with Dropbox, but I would not be surprised if both were in fact wrong.
In the closest strategy to what slack did, one would define a main product and then optimize away any prototype bloat. As far as I observed, Slack's clients stayed pretty awful and they were trying to do Dropbox's strategy without success.
