Politeness is a lame way to hide hate (unless you think things like fear are love, liking), and the potentially beautiful exchanging and actually resolving disagreements. Even worse, it hides agreements too. For with uniform politeness to all and from all you cannot know who you agree and who you disagree with, who you like and who you dislike. It creates distrust.
It’s not needed if love exists. Nobody needs to show he is nice then, for he is nice indeed.
It gets imposed by those who have some serious things to hide and the rest who agree with that get things to hide too –their honesty.