Most of the things you mentioned were a vast, designed effort by a society to build something grand and longlasting. Yet one isn't; instead, it's a commercially-minded platform for ephemeral individuals to waste time and stay very loosely in touch with a very large number of people. It's not a project being built. And, to throw my personal opinion into the mix, it's not even close to edifying civilisation like any of the others.
Well, a vast section of the items on the world heritage list was build for - let's just say, less that noble - purposes, using methods that would cause military intervention today. Yet, that's no cause for dismissing their grandness, and neither is the fact that Facebook is commercial.
