Political correctness is a means of exercising social, political (and economic) control, a degree of which is, of course, necessary; but it lends itself to massive abuse by those seeking power-political and/or economic advantage - as those in politics, business and the media always are.
In the Middle Ages, political correctness was defined by the Church, which derived massive political power and social advantage for its members from it. With the decline in Christian belief, a “moral power vacuum” arose, which has been largely filled by the, mainly secular, liberal (and not so liberal) Left.
In place of “original sin”, which only submission to the authority of the church could save us from, it is now “prejudice” (especially, racial prejudice, i.e. “racism”**), we must be saved from by our “moral superiors” in academia, politics and the media.
** Being human, we are all stuffed full of prejudices, about everything, including race, of course, which we need to control in a rational and civilised fashion, just as we need to control our sexual lusts and other aspects of “original sin”, but by demonising them as “evil” we are forced to suppress and deny them, even to ourselves, thereby providing the state (in earlier times, inseparable from the church) with an artificial and spurious source of “moral authority” as a powerful means of social control.
If you consider what a deeply tribal animal we humans are, it is obvious that racial prejudice is as natural and healthy a part of our nature as sexual lusts are, which the individual needs to be aware of, in order to exercise rational and civilised control over them, rather than allowing their demonisation and suppression by the state for the purpose of authoritarian social control.