This protection is NOT about the value of the social graph. And neither is Facebook, BTW - that turned out to be a gambit to get where they are.
And where they are is that they know everything about you (biographical info, hobbies, affiliations, marital status, number of kids, sexual preferences, web sites you visit and when), independently of who you know.
Right now, fb are only (?) using it to target ads at you, but you can be sure that all three letter agencies are cc:ed on every database update
It's about not letting Facebook track your every move on the web and beyond (or, more accurately, not let every site snitch on you to facebook).