Well, that too. But eropple (the parent poster)'s point is that social networking apps are the kind that would typically ask for this permission. Controls on this behaviour before and after the fact can work together.
Now that I think about it, doing the "find your friends" thing without uploading address book data at all would be tricky.
This is the same reason Facebook apps have to explicitly ask for permission to certain data.
It is Apple's platform, and Apple's app store. They own more of this issue in my eyes. They are the ones that make the rules and review the apps.