Why is Pinterest growing so quickly?

Everyone seems to be obsessed with talking about the rapid growth of Pinterest (myself included). I’m not sure why everyone fixates on the pinboard layout, because as this post points out, that’s not really what’s so great and original about it:

Growth Hack #4: Infinite Scroll

Try and scroll down your pinterest feed and you will never reach the bottom. The auto-scrolling technique that pinterest employs when you scroll down the page produces a state of ‘flow’ that is very easy to get lost in, spending minutes or even hours scrolling through pins without being mindful of the clock.

While he does identify several other factors, I think this is really what people should be talking about when they say they want to clone the look of Pinterest. Copying the other things he identifies as growth hacks wouldn’t hurt also.