People want what they want, and don't usually have a consistent philosophical framework to back it up. They'll just use whatever phrase they've heard that speaks to them and aren't really concerned if they take the other side for another topic. They'll say that state's rights are important when they are arguing for one thing and forget about that principal when it comes to another, and it's not limited to one party or another.

Though there is the odiousness of "state's rights" originally being shorthand for "state's rights to allow slavery". It would be nice if people trumpeting the philosophy remembered that it was the justification for a monstrous institution and a war to maintain it.