This is one of my pet peeves with even casual conversation. Someone goes "I don't like X, because Y." You point out Y is false, and the response is "Well, I still don't like X".
It used to annoy me because wanted to help people not base their views on bad information, as that's what I would want people to do for me. But now, it mostly just annoys me because of how predictable it is. You know the only good answer is to agree with them, so what's the point in even conversing?