For the same reason you do.
Except that I don't, Yellow. Anyone who has read more than one of your posts knows that you deliberately malign others, ESPECIALLY when those others disagree with you. I've certainly been known to give idiots the rough side of my tongue, but only after they've shown they have no intention of trying to behave respectfully toward others.
You see, Yellow, treating others respectfully, even when they hold different views from one's own, is something decent, CIVILIZED human beings do--or at least try to do. Jerks don't. YOU don't. And that, Yellow, is why you are a jerk, and I am not.