Children are by nature self-centered. Now, those with quality parents often learn to regulate their behavior by their teen years, but many do not...

IMO trying to make all teenagers nice to each other would be like trying to empty the ocean with a bucket.

I think it is more likely effective to work on the other end of the equation. Teach those growing up how to deal with being insulted. I recall a saying that parents USED to teach, "Sticks and stones, will break my bones, but names will never hurt me.".... while there is a certain truth to the idea that words can hurt, the biggest factor is in how credibility one puts in the speaker...

If someone you already don't respect, calls you an asshole, it will most likely roll off your back.

But if it someone you respect or like... the insult can have a much greater impact.

IMO since insults WILL be tossed around anywhere there are teenagers, it is a much better plan to teach them to take insults for what they are worth. To not take them too seriously.