Around the healthcare debate specifically, there were a lot of people who talked about the restrictive policies that artificially limit the supply of doctors as well as the policies that prevent the creation of more hospitals.
When my dad was growing up, his father was a mechanic and he really just wanted to go be a mechanic to work with his dad...who told him that it wouldn't support 2 families. So instead...my dad became a dentist. Don't get me wrong, he's very smart (particularly with math) but how many people could be doctors? How many people could handle the curriculum at MIT, Harvard, Stanford, Georgia Tech, Vanderbilt, etc?
My guess is that it's a whole lot more than are actually admitted. Further, is the curriculum at these schools that much better than everywhere else or is it more a factor of surrounding yourself with highly motivated peers that makes it better?