[snogglethorpe]

Sure, but ...

I think the main differentiator is the degree to which the help is generic—if person X could have been easily replaced by hundreds of others, X was probably not all that crucial to changing-the-world-process-Y even if they provided a great deal of assistance to Y.

For instance, the people who made the food Larry and Sergey ate while hacking late all those nights, had a very direct effect on the creation of Google: they kept the creators alive! But food providers are easily replaceable (cold as that sounds) in most cases, so it seems a little bit silly to say that the delivery guy for Sergey's favorite chinese takeout "changed the world."

So when it comes to VCs, it seems the relevant question is: absent a given VC, how easily could the entrepreneur secure funding elsewhere? A very, very, risky project that requires tons of money may indeed have an extremely difficult time raising enough funding, in which case the role of a VC that "takes the leap" is much more crucial than it might be otherwise. In other cases, VCs may be more akin to interchangeable service providers.

[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?