Courtesy isn't a privilege, nor a suggested way; it should be a law. There is no way anyone can get anything from tantrum acting, not a well behave answer nor a nice and polite feedback… I do not understand those who are not courteous. You can be mad at something or someone, that still does not justify the rudeness. I grew in suburb of a big city with tough kids and I got bullied a lot, and when I say a lot I mean: beaten by 4+ persons at a time, the iron taste of blood in my mouth, I knew only too well. Despise these jerks, I still do not see how rudeness could solve that.
I think we need more schooling on emotion control. If we were aware we are mad, then knowing fully well the steps of that strong emotion, we would wait a little longer before sending harsh replies or rude tones. And knowing is the beginning of solving!