There is an advantage, but perhaps not the one you think. The advantage is not the brand, but that you know lots of smart people you can recruit to join you. Which Drew did, starting with Arash.
Completely agree that the major value of great schools is better schools attract smarter people, who often make better founders.
Like you said, great schools attract smarter people (not all of them!) and that makes for a more competitive environment, which in turn churns out more driven/analytical kids.
I know a TON of idiots who went to Stanford and Berkeley. And I know a dozen or so extremely successful entrepreneurs who never went to college.
There it is, you are taking the brand in account, even if it is not completely fetichism, because it's experience based. If you count on this advantage before it happened, than it is brand.