It's enough because if you're doing it for facebook, you have to do it for every site. Which would require some kind of government provided authentication for e

It's enough because if you're doing it for facebook, you have to do it for every site. Which would require some kind of government provided authentication for everyone logging in. Korea does it, which requires an Residents Registration Number for many of their sites, which is frought with its own problems. The amount of work required to put in such a system would also be prohibitive, since most countries would have seperate systems, and each one of these would need to be accounted for. It'd raise barrier of entry for sites, since along with other infrastructure, they'd need to set up complex identification rules (granted, after some time there will be libraries for that. still, it's another step they have to take). It'd be a soggy mess to set up something like that.