> Pinterest provides entertainment, product discovery, and community.
This is kind of a non-statement. You could say that just about any internet based social network startup provides "community" and "entertainment" -- and yet many completely fail. This is quintessential grasping at straws and a posteriori reasoning.
> Snapchat enabled a new type of communication by removing self consciousness.
So did Yik Yak, so does IRC, so do anonymous forums, so does Kik. Again, this is kind of a ultra-general non-value value proposition. Why Snapchat got funded has nothing to do with the idea -- and everything to do with traction.
> Airbnb provides quality lodging at low prices.
So does hotels.com or (if you haggle a little) Craigslist.
> Facebook provided authenticity, exclusivity, and increased information density through timeline.
The timeline wasn't around when FB launched (back then we had the wall). I'm not even sure what "information density" means (or if it's even a good thing), it seems like 20-20 rear-view justification for FB's success. MySpace probably provided more authenticity, anyway (I could customize my page way more).