If going to an elite college gives you a better chance of reaching the top, then hirers will come from elite colleges.
If getting a CS degree gives you a better chance of reaching the top, then hirers will have CS degess.
Getting a CS degree does not give you a better chance of reaching the top. It gives you a better chance of reaching the upper-middle.
Of course this system eventually breaksdown. But for Eton school it's worked since 1440, for Oxford since 1096, Cambridge since 1284 - but eventually it will break down.
Universities pretty much had the monopoly for highly specialized knowledge until very recently. The companies, public and students waking up to the fact that knowing your rhetoric & poetry ain't so valuable any more IS the system breaking down. Right now.
You'll rather hire from HN than from Oxford.