To understand the mechanism by which something so incoherent and labile as political correctness has attained authority over our societies, it is helpful to consider the parallel case of fashion.
Fashion changes, that is its essence; it changes, and people change with it. They change despite the costs, despite that they look ugly (may permanently damage themselves); they change despite that this involves repudiation of their former selves, their former choices.
They go with fashion because *not* to go with fashion is to mark oneself, to separate oneself.
Once fashion is a going-concern, then it is tyrannical - it is authoritative.
Who are you to set yourself above fashion?
What kind of pumped-up, arrogant - or lazy and slobbish, nutcase and loner - would stand apart from the movement?
Do you think you are better than fashion, eh? Better - that is - than everyone who does follow fashion?
But why does fashion change - fundamentally, why?
Fundamentally, because fashion is senseless and incoherent, so it must change...
Sometimes, randomly, fashion hits upon something right and true, useful and adaptive... But no matter! That will be changed just the same as if it was ugly, vicious, lying.
Fashion is a process, and the process is primary - the process is hierarchically dominant over content and over other processes.
Fashion, the change of fashion, is not just an expectation, it is certainly not a choice - it is an imperative. Social authority - which used to exert social pressure to impose (coercively) *specific* behavior - now exerts itself to impose (coercively) change in specific behaviour.
The only concession is that of a choice of specific changes (e.g. various rival cults, groups, trends). But that is only to amplify the process, and to devalue the content of any specific choice.
So, fashion is about not being excluded, about obedience to change, about attitude to those who do *not* change in the required direction (who refuse the offered options - taking another option instead or sticking to the old).
But the great, great advantage is the sense of superiority over those who are slower to follow fashion or who refuse to follow fashion!
This is the same with PC - the great benefit is the sense of superiority over all previous generations and over the great non-PC mass of the world.
It is the sense of being linked to a process, not a specific content - and a process can never be made obsolete - it is the process which itself renders obsolete!
Think of a teenager's attitude to fashion, think of the leftist attitude to political correctness; think how the teenager feels superior to all the old squares the grown-ups, think how the politically correct feels superior to all the previous generations, to the conservatives and reactionaries alive today.
Of course (think both) the present state of affairs is imperfect, but it will not last, something else will come up which will correct the imperfections.
But the 'corrections' of political correctness are like the 'corrections' of fashion - colour corrected by monochrome, narrow trousers by wide, tight clothes by loose - one specific correction amidst random permutation...
It is not progress it is change, or rather it is the process of change relabelled as progress.
It is conformity relabelled as perpetual rebellion.
But it is a conformity against specific stuff - it is not conformity in favour of anything - because any specific *that* which is (currently) favoured *will* change. Only the process of change will be retained.
This is a hierarchy (all else subordinate) - but with no specific content being superior instead with change (defined as progress) given primacy.