I found the purpose of insults! Squee!
I completely disagree with both Stephan Molyneux and in fact most of the progressive tradition. Insults and 'hurt feelings' are not abuse when used correctly.
Up front, there is never any reason to insult your children. Correct, yes, insult, never. That is abuse. Further, if you insult with any intention but the one below, it's abuse, but only because it is in the general meaning of 'abnormal use.'
The purpose if insults is to correct misbehavior and to drive away undesirables.
In a conversation between two people, one does something contemptible, and so the second hurls an insult. This allows One two options - either correct the behavior, which will halt the insults, or decide that Two is not someone they want to hang around, which will halt the flow of insults. In other words, two natural responses to insults - to correct, and to ostracize.
Used this way, insults are not attacks. Any response that heightens or sustains insults is cowardly on the part of One or violent on the part of Two. This is the third response - further insults. Starting a fight is always a bad idea, and so this is hardly unique to insults.
I would like to give special attention to insults directed at something One cannot or will not change. They are also abuse, that is, abnormal use. If you just want to drive someone away, insult them for being annoying, not, for instance, fat. They might just surprise you by becoming not-annoying. If so, then you won't want to drive them away, so don't start insulting them for being fat. Such abnormally used insults are also dishonest.