One time I asked why, since cgroups and the pattern of container based deployment had been popular for a decade before Docker started, that containers are so popular right now. We ultimately decided that someone constructing a really easy to use suite of tools around the concept was the reason it has all this love and growth.
Not that I totally disagree, but, signing up for Slack is easier than using NickServ for the average person. There's a bunch of features that make HipChat, Slack, Hall et al easier to use than IRC, especially for someone who doesn't want to learn anything new.
Just worth thinking about...