PC is a form of censorship designed to quell free speech and, thus, quell the spread of ideas.
It is all around us.
A related tactic is the the politics of personal destruction, wherein the person, rather than the ideas expressed by that person, are verbally attacked. Regrettably, some FR posters use such a tactic when they are empty of facts to support their contentions.
PC and its related 'instruments' can take many forms, all designed to direct the social discourse.
In discourse and debate, defining the terms dictates the outcome.