Google also has a list of schools that are considered top-tier, and if you're not from one of those, you're unlikely to be hired. I don't believe Google has always been this way--and I think the pressure to raise the hiring bar in so many artificial ways comes not from any elitism, but from the fact that Google is hiring way too fast, and the folks at the top know it. By ruling out everyone below a quite high academic threshold, they've cut down the number of applicants under consideration.

I suspect, but don't know for sure, that if you have a long track record of producing good results, you can still get hired by Google. I received a recruitment letter from them, but never followed up by going through the hiring process to find out if someone with a couple of two year community college degrees (and no computer science classes at all aside from AP high school classes--I tested out of all of the computer-related classes for my degrees) could get hired there, based on the strength of accomplishments, alone. The letter came two days after I accepted funding from YC, and a few months after we started making money with Virtualmin, so it wasn't really of interest at all. But now that I think about it, it would have been an interesting experiment.