I normally don't comment on these "PC" threads because it becomes pointless. PC is effectively a snarl word, a thought terminating cliche. It is, ironically given its origins, an attempt to shut down debate. Modern debate and discourse seems to be chock-full of such "thought-terminating cliches" from both right and left. Any nuanced discussion can be avoided as long as something can be labelled with a handy, ill-defined pejorative. "racist" "sexist" "snowflake" "SJW" "anti-Semitic" "homophobic" "misogynistic" etc. then debate is no longer useful and in some cases not even possible.
The principle behind it is easy to fathom. Thinking careful about grey areas is hard and uncomfortable. It may lead you into awkward, conflicting places. Far simpler to just stick a rhetorical yellow star on a point of view and have done with it, problem solved. Plus there is a ready-made mob out there in the social media sphere who will lazily and thoughtlessly jump in to support/condemn whatever position you take/decry. You can feel vindicated about absolutely anything at the drop of a hat. No actual argument required, no work to be done at all.
In todays world of social media, the people who take rabid exception to "PC" are normally those who do not wish to be courteous or polite, and call the trappings of being a decent person "just being PC"
PC is a snarl word, used to justify being rude and insulting, and claiming that anyone offended by bigoted, misogynistic, or homophobic speech is just being PC.
For a type of PC I believe most people find ridiculous: The first thing to pop in my mind was something from many years ago, demanding to stop the use of the words "master" and "slave" in hardware.
https://www.snopes.com/fact-check/masterslave/