I don't think that "liberal" and "conservative" are empty labels outright. However, they seem to be for the author of the post I was responding to: no substance, just bags to hold reflexive emotions that disguised themselves as opinions.

These two words lend themselves to that, because of what we use them for. I would not reject them, though. Naming things remains useful; and whatever words we would replace these 2 with, and we would, out of necessity: they'd receive the same treatment.

The words are not the problem here. Using them without thinking is.