I'd love to know more about why did Slack were able to get so much traction and raise that much money compared to Flowdock/Groove.io/Hipchat. I've used Flowdoc

I'd love to know more about why did Slack were able to get so much traction and raise that much money compared to Flowdock/Groove.io/Hipchat. I've used Flowdock in the past and tried Hipchat too. I've also been a huge IRC fan when I was younger. I don't see that much of a difference between those and Slack.. Maybe: - More intuitive for people who don't already know IRC. - Really cross-platform - Well integrated with various tools people love. - Very good "on-boarding" flow. But still, the difference in term of traction is massive, am I missing something? Personally, I think we switched because I was a bit frustrated about the status quo. IRC was too complex for non-tech and didn't have a good cross-platform integrated solution. Hipchat app just felt so clunky and ugly.. same with Campfire, it felt really old. I've used and liked Flowdock but I thought it was just too much with widgets all over the place and smart inbox, where what I wanted was "just" a "IRC" I could use with colleagues. Thoughts?