[nailer]

Sure, but FB had a smaller network than Myspace. Instagram once had a smaller network than Flickr. They grew the network through better UX (ok it's hard to say now with their MS-Word style shotgun blast of icons, but FB was once miles ahead of MySpace).

[pathseeker]

No, FB initially grew because of exclusivity of the network. I only signed up because it was for college people only at the time. I didn't care about the interface at all, just the content and who was posting that content. It was absolutely not "myspace with an improved interface".