[RobertoG]

I think that there is a good explanation for that emotional reaction.

We have not evolved in an environment where you interact with "complete strangers you don't see and will never meet". So, you can't allow others take the upper hand on you too much. That is even more true if third parties are observing the interaction.

You can see the same, for instance, in how pub fights start for the most stupid reasons. Even if is a big city and they will never meet again, they can't just leave it alone because when our brain was programmed it was not going to be only an interaction. And if your friends, or god forbid, attractive women are present, then the contenders are trapped in the situation.