“That may be true, but “political correctness” is more often used, in my opinion, to attack legitimate complaints by marginalized people about the insulting rhetoric used against them.”
On that I totally agree, and it is one of the reasons that over sensitivity, or claiming terms like master/slave processors are racist, feed into that. PC has been used to cover up for politicians who say horrible things, or racist things, there is no doubt; but when someone makes a mountain over a molehill and finds racism or sexism over trivial things, it feeds the fire of the Limbaughs and Hannity’s and the like, they can cite trivial things as example of the PC police, how stupid they are, but then de facto use that to try and make, for example, someone chiding a Donald Trump for some of his stuff which is vile, as being ‘pc’. When you fight an enemy, ignorance, bias, ugliness, fight the real thing, fighting at shadows or at things done with no ill intent trivializes the real fight.