I'll admit I've used it for similar reasons. What I really should be saying is "I'm sorry, but I don't want to talk about this right now." Maybe I'll even be brave and say "I don't want to talk about this with you." but it's rare for me to find a person I don't want to hear at all from. That usually comes up because they've already made their arguments, and I've already accepted or rebuttal the points to my own satisfaction. At that point they'll talk themselves into circles looking for justification for parts of their stance, but unable to articulate it themselves. I'll listen to anyone's views at least once, given I'm in the right mindset, but I still wouldn't date someone I don't morally agree with. Life partners should have higher standards than conversation partners, and aligning values is a bare minimum for relationships.