I don't think anyone "needs" to graduate from a top college. But I think it's also true that the quality of the engineering education at, say, MIT is much better than the quality of the education at an average university. Part of that is the quality of the lectures and lecturers, but another major factor is the environment -- the quality of your fellow students, and the social norms in a place like that.
I think that is even more so for graduate programs, but significantly less so for degrees in arts or the social sciences -- if you're taking poli sci, I think most of the advantage of going to Harvard is in the social connections you can make.
I think the point that Alex was trying to make is that if you are not intelligent enough to realize that it doesn't matter that much, you probably are going to need all the credentials you can get.
The engineering education at Pitt is solidly mediocre, yet we're still reasonably high ranked. Most of my upper level IE classes have 60 people which is unreasonable and really hurts the quality of learning. Still, engineering, at least, is in demand enough that Pitt graduates don't have any trouble finding jobs around Pittsburgh.
