What's the point of being rude?

I absolutely HATE rude people! I mean who doesn't? But a lot of people can probably handle them a lot better than I'm able to. I take it really personally as soon as someone is being mean without any reason. Today I asked someone for help and got a rude reply and a door shut in my face. Clearly this woman must have some serious personal issues, but still...who does that?! I've heard the saying" be kind to everyone you meet because everyone is facing some kind of a battle". That's probably very true. Only wish more people would take it to heart.