In startups, we often tell each other that "the idea is useless", that is, startups are not about the technical details of the idea, they're about the human-to-human interaction of people and your business. This is also true about data. Startups are not about the data . A dozen companies did what Dropbox did, but there was only one Dropbox. Everybody did search, but there is only one Google, and so forth. Yes, people…
Maybe I'm missing something, but DropBox was just a very well-implemented GUI for backing up files - there was no "special sauce data".
As for Google, one could argue that their data (or their index) was one of their competitive advantages. They started crawling pages back in 1998. They basically have a 15 year head start over any new competitors that want to enter the field today. And their index is vastly superior to Bing's/Yahoo's.
So I would disagree that startups are not about the data. For a lot of them, without the data, they'd just be a fancy, useless CRUD GUI.