The left doesn't believe in democracy. Ever hear them gripe after an election that the public is too stupid to vote "properly"?
Political correctness is not about debate. It is about despots making the liberal agenda the dominant viewpoint. Wouldn't want to be guilty of thought crime. That's what happens when people are free to think for themselves.
It would seem to me that morality would be the one issue for which widespread public ignorance would be no handicap to proper decision making.