It seems that political correctness represents a 'turn' in Leftism.
Leftism can be seen, for most of its history, as a reaction against Christianity; a denial of the reality of God and a compensatory deification of the human.
But PC has turned against the human, and is now a deification of the system.
Now the cutting edge of the Left is not about gratifying individual preferences, nor about self-development: these must be subordinated to abstract systems for allocating 'goods' to ensure 'fair' outcomes.
In this sense, administrative systems of group preferences ('affirmative action') are the epitome of modern PC Leftism; monitoring and regulatory guidelines becoming ever more numerous, interactive; concerning smaller units; and penetrating ever-deeper into the capillary level of human life, the interstices of human interaction.
The modern Leftist hero is no longer a spontaneous, self-validating spirit of godlike autonomy but an expert and obedient functionary who has internalized all the rules such as to satisfy all the quotas simultaneously.
What counts as 'fair' is necessarily very uncertain, given that humans don't really matter anymore; but if the PC Left is unsure about what counts as fair, it is very sure about how fairness should be achieved: fairness is an outcome of abstract process (laws, rules, regulations) that over-ride individual choice.
The Left is no longer about a society based on equally free humans all of whose needs are satisfied - since the PC turn the Left is now about humans being an unfortunate (but perhaps temporary) impediment to the smooth running of impartial administrative systems (which systems currently involve humans, but perhaps temporarily).
It is no longer the job of The System to fit around human desire, as for the sixties radicals; but the job of humans to fit into and support The System.
Something analogous is, of course, also axiomatic in the Gaia worshipping Green Left. The system is Gaia, and humans function mainly to damage this system. What is required from humans is at least support of the Gaian system - but ideally mass suicide.
Th strange thing is that this U-turn is hardly noticed on the Left, even among those (such as the Baby Boomer generation) whose own lives have described the trajectory from valorizing individual freedom, impulse and happiness down to the anti-human abstract impersonality of PC.
In the space of forty years the Leftist Utopia has gone from being a hippy commune of free love, dreamy drugs and idleness; to a politically correct society in which every thought, word and deed are monitored and regulated by bureaucracies that are assumed (on the Left) to be intrinsically benign.
The difference is not subtle: you'd have thought they might have noticed...