I think the discussion is usually more complicated than people give credit for. Political correctness exists on a spectrum, with plenty of disagreement about what's out of bounds, and general agreement that certain behavior is unacceptable. A board of education member who says he's not going to educate women because their only role is to make babies is going to be out of a job, but this would technically fall under the umbrella of political correctness. That suggests that there's a level of political correctness that we can accept as a society.
It goes too far when it's hard to have honest discussions about things that may be true. It's catastrophic when we can't have honest discussions about things that are true.
Jonathan Chait wrote about this in 2015, but the problem's gotten worse, partly with Trump representing the alternative to political correctness.
https://nymag.com/intelligencer/2015...ng-to-say.html
It's more of a problem in academia and certain social media circles, where liberals don't have to worry about arguing with moderates or conservatives. But it has started spreading elsewhere, especially left-wing cultural institutions.
One worry for the left should be that political correctness is a system with significant support that makes it too difficult to talk about certain topics for fear of backlash from your side. That means that the conversation could be limited to the most radical members of the left, and the people who aren't as worried about being labeled by them (ie- conservatives who get to limit the fight to the most extreme members of the opposition.)
The Medium article is about three years out of date, although the controversies are rather ridiculous. It is also accurate in pointing out that PC policing is pretty much incompatible with classical liberalism.