They blew it. And a few generations get to pay the price. Boy, do I feel "engineered."
Some folks believe, and it's actually been quite well documented, that the Federal gubmint intentionally dumbed down the population.
Check out The Deliberate Dumbing Down of America by Charlotte Thomson Iserbyt.
This book uses gubmint documents obtained through the FOIA, along with news stories that, in many cases were run once, then disappeared from public view, to show this gubmint policy goes back at least as far as FDR.....and maybe farther......