Forget CRUD applications. Most of the work at most companies, including the usual Big Ones, simply isn't that complicated for anyone with just about any technical degree. On your scale most of it, almost all of it, tops out at like 50-60.
These companies set the bar at 70+ for a number of reasons. Their own egos ("I only work with 'the best' so therefore I'm also 'the best' and don't want to water that down"), status signalling for the companies, to keep bright young talent from starting a competitor, etc.
Good luck convincing Google (or Netflix / Amazon / Microsoft / any other major company) that anything they do is 'just a CRUD application'. Even when it's true, they'll never admit it.
It's pretty easy to make a bag of garbage; it's non-trivial to make 100M bags of garbage.
Even if they're making CRUD apps, making tons of high-availability CRUD apps that work against dozens of services your team doesn't own that can serve huge fractions of the globe requires non-trivial coordination and skill. (Not that all those companies do is CRUD apps, but even if.)
I'm not sure it's as jard as those companies make it out to be -- but it's not "just CRUD apps", it's the logistics of CRUD apps spanning the globe.
Are CRUD projects really the most guilty of only hiring from "elite" schools?
Sure, there are software jobs where you're setting up wordpress blogs, but there are plenty that require you to think about algorithms and how your database actually works in order to do them well.
These companies set the bar at 70+ for a number of reasons. Their own egos ("I only work with 'the best' so therefore I'm also 'the best' and don't want to water that down"), status signalling for the companies, to keep bright young talent from starting a competitor, etc.