I strongly disagree when there are "millions" of users, and the product in question is a web-software startup. The early adopters of these products are very likely to be small, tech-savvy businesses, which is definitely one of the core HN audiences. Not to mention a lot of us just follow software startup news in general...
It's a collaborative notes and documentation suite. Lots of people use it -- including the company I work for -- but it's not "disruptive", isn't surrounded by legal controversy that I'm aware of, and mostly just delivers value for money. Which makes it the opposite of what gets talked about on HN.
