How is that stupid? It's true. It's cherrypicking a subset in order to reinforce a point, but it's still true.
Flip it around. "In previous generations the college educated were smarter because we didn't let the stupid people into college". As an observation, absolutely true. Not particularly meaningful in itself. It's an observation rather than an assertion.
But it does lead to a more meaningful question. It's a different question. The relevant question is "compared to previous generations, how stupid are OUR stupids?" This is the "was the education effective" metric. That metric will lead to assertions which will probably be meaningful.