Quite the opposite. Learning can only happen, if there is some kind of feedback. If the other side doesn't notice that something is off in our communication, because I do not signal displeasure about their rudeness by being rude myself, they cannot change their behaviour.
Most of the communication in the internet degrades, because information flow is lacking. If you answer politely, you can, when meeting in person, still convey an air of annoyance. You can signal the other person more than just what is being said. In written communication, this doesn't work. All the polite subtleties will be missed. All the cultural cues, like being overly polite or formal to signal distance, don't work because there are just too many cultures meeting, and you can't calibrate your interpretation to the other side like you do "at home".
This means that in the internet, you need to be more direct. You need to say what you mean. And if you need to dismiss somebody, you need to be explicitly dismissive. If somebody is rude, you need to be rude and tell them about their rudeness. Being polite for the sake of politeness is misleading, inducing the other side to continue their errorneous behaviour up to the point where things really degrade into an unpleasant situation.