That's a provocative statement, here's the justification:
Instagram had "only" 18 employees. Wherever you are, will1000, hiring 18 employees of the caliber who built Instagram for 18 months would cost you $2M. Instagram was able to pay for them with equity, instesad of starting with $2M in the bank.
The direct reason that this doesn't work outside silicon valley is that outside silicon valley you, will1000, will not work for me for equity instead of a market salary. That is only possible in Silicon Valley.
In other words, you don't want to believe that a % is worth anything, and that's why you won't accept equity based compensation (outside silicon vallye).
look in your heart and you know it's true. what's the lowest salary + equity compensation you would accept?
Could instagram have afforded you?