When you're coordinating with others, it's easier to get to a harmonious result when you're already mostly aligned.

MySpace allows experimentation but is overwhelming, each page is more different than alike.

When you view a random friend's page, you have to orient yourself to make sense of the social information, because the design variance overwhelms it.

Facebook was on tight rails... but made the social part pop, because all that was different was the person's social information.