[nostrademons]

So, then you get into the question of how replaceable the founders are. For Google that's probably "not much", since there were some pretty big intuitive leaps that were non-obvious when they came out. Even then, however - a lot of people I know say that the inflection point in Google's success was when they hired Urs Hoezle as employee #9, because he had been through the process of architecting a massively-complex system before (he founded the startup that eventually became Java's HotSpot compiler).

But for Facebook - millions of programmers could have written Facebook as it existed in 2004. Mark Zuckerburg did, and he got the billions.

And Twitter - millions of programmers could have written Twitter as it existed in 2006. Jack Dorsey did, and he gets the reputation (and the paper billions).

And Instagram - millions of programmers could write Instagram. Kevin Systrom did. And he happened to know Adam D'Angelo, who introduced him to Marc Andreesen. Who was the critical link in the chain? Kevin, Adam, or Marc?