OK, just as a point of correction, pretty sure it's the case that we have the words "Centrist" and "liberal" being tossed around for all the positions you describe here. The pejorative implication of being a Centrist or liberal is that you're basically what used to be called a soft conservative, someone who gets edgy around anything vaguely new or progressive and likes the status quo. The term "alt-right" is reserved for people who see themselves as engaged in a culture war with the left, who feel they've got to take down the bad old '***s'. People get branded alt-right if they're suspected of deliberately targeting left-wing or minority writers with as much bad publicity as they can muster. There's certainly plenty of that going on, but I don't know what the actual numbers are.