I.e. It becomes about controlling mind-share. Calling something out as "unfair", "biased", "propaganda", or "fake news" is one way of controlling the amount of mind-share it has with people that identify with it. So you can't just "let someone" have their "wrong" opinion, you have to "correct them". That is precisely what political correctness is, it's to "put down" unacceptable opinions with public witch hunts and legal pressure. I have no idea when it went from "leave people alone" with their probably "wrong" opinions, into "omg, you're not allowed to think/say that, you must be sexist/racist/homophobic and we'll make life a living hell for you, and we'll get you fired".