Why do conservatives and libertarians generally eschew political correctness? Because we take individual persons as they come, and evaluate each them on his merits.
That is to say, we reject stereotyping, and political correctness is just another form of stereotyping. Instead of insisting on something foolish like “all blacks are criminals”, political correctness leans the other way and insists that it is wrong to believe or say anything negative of blacks — or of any other group that has been condescendingly identified as “victims” by leftists.
Group differences matter mainly to the extent that they affect the likely success or (more likely) failure of government interventions aimed at defeating human nature. They also matter to the extent that human beings — including members of all racial and ethic groups — tend to prefer like to unlike (e.g., the preference of “liberal” white yuppies to live in enclaves of “liberal” white yuppies). But such matters have nothing to do with the conservative-libertarian disposition to treat individuals, when encountered as individuals, with the respect (or disrespect) due to them — as individuals.
In that regard, the conservative disposition is especially instructive. A conservative will not rush to judgment (pro or con) based on superficial characteristics, but will judge a person by what he actually says and does in situations that test character and ability. For example, I distinguish between leftists of my acquaintance who are at bottom kind but politically naive, and those whose political views reflect their inner nastiness.
Leftists, in their usual mindless way, take the opposite view and presume that the superficial characteristics that define a group count for more than the character and ability of each member of the group. Political correctness is of a piece with the intellectual laziness that characterizes leftism.
Intellectuals and Capitalism
“Intellectuals and Society”: A Review
The Left’s Agenda
The Left and Its Delusions
The Spoiled Children of Capitalism
Politics, Sophistry, and the Academy
Subsidizing the Enemies of Liberty
Are You in the Bubble?
The Culture War
Ruminations on the Left in America
The Euphemism Conquers All
A Dose of Reality
Non-Judgmentalism as Leftist Condescension
An Addendum to (Asymmetrical) Ideological Warfare
The Left and Violence
Four Kinds of “Liberals”
The Vast Left-Wing Conspiracy
The Left and Evergreen State: Reaping What Was Sown
Leftism As Crypto-Fascism: The Google Paradigm
Leftism (page) and related bibliography