And, the takeover of academia by the left allowed them to decide who excelled in grades, test scores and performance. They were the judges of those things. Education became indoctrination.
True to a large extent, especially in the liberal arts, but it's definitely difficult for anyone to politicize the hard sciences themselves. (Of course, the "global warming" theory, e.g., would not be "hard science," since long-range climate change is still a subject reaquiring much development and clarification.)
The best the elitists can do is require political fealty to the ruling ideology as a condition for gainful employment in a hard scientific area. But even the Politburo in the Soviet Union couldn't tell their scientists how to put a cosmonaut into space, for example, nor how to build nuclear weapons. There's no way incompetents could survive long in the hard sciences, no matter who was judging grades, test scores, and performance.