Those places do care about school name to the same extent. You'll get a junior position there, if you have a Harvard/Yale/Princeton degree, but you're not advancing unless you come from a well-connected (and likely wealthy) family. Attending a top-tier school is often just a proxy for wealth and connectedness. The companies you mentioned keep the prestige of the company high by hiring from the Ivy League, but the unconnected hoi polloi end up doing shit work for a decade until they figure out they're in a dead end.
That's really not true at all and I don't know why you've convinced yourself that it is. Obviously having connections can give you a leg up but most successful people in these industries don't have family in high places and it's not a prerequisite to ascend through the ranks. Why would so many people enter finance and consulting if they thought it was a dead end? Are you arrogant enough to believe that it's because they are dumber and less enlightened than you, and unlike you they don't know what they are doing with their lives?