Actually, you are referring primarily to the liberal arts portions of those schools.
It is (or at least it was) a different story in the science and engineering departments. They put up with conservative there because liberals are too stupid to succeed in those departments and they need them to bolster their reputations as something other than indoctrination centers for people who will never hold productive jobs.
Agree, the STEM majors are not mis-educated in the liberal arts, but they tend to be undereducated in the liberal arts of the Western Canon. That too is a deficit.