They thought that all the poor oppressed blacks would become engineers, doctors and raise the GDP by 200%. That's where liberal fantasies hit the rocks. They view human beings like lego blocks: interchangeable and all capable of performing the same function. Just like blocks, they're only a different color on the outside but are the exact same thing in the inside. All that's needed is some social engineering and you can mold any man into anything you want.

It was the same idea behind Marxist communism, that you can throw out the sons of nobility from high office and replace them with the sons of day laborers and get the same result. You could throw off successful farmers from their lands and give the land to criminals and laborers and net the same yield.

Ultimately, these delusional assumptions led to the failure of communism and its now leading to the failure of liberalism.