The VCs add little but are kingmakers who decide who can buy the talent and who can't. For historical reasons, they're geographically concentrated.
Also, most of the Silicon Valley "innovation" is a joke. Clinkle? Snapchat? Uber I will give high marks for potential, but it was founded to facilitate date rape (to give young sociopaths in San Francisco the experience of being a "baller", to use a direct quote) and it was only later that its investors took note of its long-term possibility to be something more.