People are reasonably worried about the difficulty of changing schools mid-stream and whether they'll be able to pick up smoothly at the more prestigious school or be at an academic or social disadvantage relative to those who did their whole degree there. Also, these choices are faced primarily by young people who have no college experience and often little life experience in things like fiscal management. Meanwhile students are bombarded endorsements for the idea of being accepted to a prestigious university, whereas announcing that 'you're going to start community college!' is equivalent to signaling that you will be spending two years on an uncompetitive track.

I think it's disingenuous to ignore these differences, or to assume that employers will necessarily take the broader view. I am not asserting that the approach you describe cannot work out very well for some individuals.