I agree with your synopsis, but I disagree with the premise.
Any writer knows that there is nothing more terrifying than the blank page. In social networks, it is the empty friends list.
All of that 'pseudo-user-generated' data that is pooh-poohed gives a new myspace page a warm and fuzzy feeling that is would be missing from a "build-it-yourself" network.
It reminds of Joel Spolsky's take on Jakob Neilsen:
"Every time I read Jakob Nielsen," I wrote in 2000, "I get this feeling that he really doesn't appreciate that usability is not the most important thing on earth. Sure, usability is important (I wrote a whole book about it). But it is simply not everyone's number one priority, nor should it be. You get the feeling that if Mr. Nielsen designed a singles bar, it would be well lit, clean, with giant menus printed in Arial 14 point, and you'd never have to wait to get a drink. But nobody would go there; they would all be at Coyote Ugly Saloon pouring beer on each other."