The thing is that political correctness, in the sense of an orthodoxy that exists in terms of what opinions you can express without ostracism in a community (particularly a progressive community), is a very real phenomenon, and can be quite pernicious. But in the sense that it is generally used by conservatives at present, it is basically a catch-all snarlword for anything that they disagree with, but especially for oppressed groups standing up for their rights. And it is used so much more frequently in the latter context that I question its usefulness in the former.