My out-pourings on the topic of political correctness have now, more or less, stopped; and I am starting to pull things together.
Karl Popper commented (in his autobiography Unended Quest) that definitions are of limited value; and can indeed serve to close off enquiry.
Definitions come after enquiry, and serve merely as a convenient summary.
My understanding of the nature of PC has developed as my ideas have clarified. I would now consider PC to be an evolutionary development of socialism/ communism - it is what the New Left of the sixties became.
In particular, PC is post-communist in its anti-utopianism - and its principled anti-humanism.
In its early ideal form communism was intended to liberate human individuals - after humans had been remade/ or had their false programming removed, then the state apparatus was supposed to wither away.
Of course, when this showed no signs of happening then communism became hypocritical, careerist and corrupt - but PC has arrived at the corruption, careerism and cynicism of late communism.
Yet there is much more to PC than this: PC is underpinned with an extraordinary anti-human kind of idealism, a state-ism, in which humans are regarded as the root of all evil and the abstract state embodies virtue (through its abstract processes, its procedures, laws, regulations, bureaucracies etc.)
So ultimately the idealistic PC intellectual is something like the idealistic communist commissar who was working to make his own job unnecessary; the idealistic PC bureaucrat is acting to make human judgment and power not merely unnecessary but impossible: all important human decisions are to be transferred to abstract system.
Individual agency is replaced by the state.
Thus PC is, in its aspiration, the only wholly and permanently totalitarian ideology to have gained any currency and traction in the history of the world.
That is why political correctness is evil; and why PC must be denied and opposed by each individual human person, without regard to the possibilities or probabilities of effective resistance.
Even if resistance seems doomed certainly to fail in this world, PC must be resisted.
Because resistance to PC is not 'futile' - quite the opposite - life has meaning and purpose in the act of resistance.
It is embracing of PC anti-human abstraction and the annihilation of human agency which is 'futile': indeed, its futility is guaranteed.
(Hence the tidal self-loathing unto despair, avolia and socio-personal suicide of the PC elites.)
PC is not, therefore, merely a political matter: it is existential, it is ultimate.