Idk about the "Prestigious Universities earned their fame for the most part" when implying that then causes their students to become way smarter.
IMO to compete in the "college admissions race", smart/motivated students will often compete like crazy to get into the prestigious university system. So because so many very smart/motivated students compete to get into the programs, the prestigious universities get their pick of top tier students who will end up graduating who could turn out to be smart/competent programmers regardless of the actually quality of the program.
I'm not saying these top schools have crap programs, I'd imagine they do have great programs as well, but I'd guess those same students would become good/competent programmers coming out of any program.