People who accuse other people of being “politically correct” are actually stealing a bit of ancient Communist Party lingo from the 1930s, when it was an approving reference to people who were adhering to the party line. When the term started to reappear in the 1960s, it was a fairly witty recycling of an old, forgotten term. There’s not much humor in it now.
Self-censorship is the most effective form of censorship. When it can be arranged, it leads to a situation in which people don’t want to say what other people likewise don’t want them to say. Self-censorship also has the advantage of leaving no footprints.