Re: My Sensei can beat up your Sensei
The best fighters aren't necessarily the best martial artists. I think one of the reasons for clubs to avoid competition is because students want to learn to defend themselves as best as possible i.e. what is the best that each student can achieve. Many of these students would never be good fighters, but they could learn to defend themselves against an attacker. Certain individuals will have a predisposition to fighting, and, whatever the art, they will have an enormous advantage in arranged fights.
An important aspect of aggression in the street is that you don't have to win - you just have to make it hard enough for the attacker such that they will stop trying to hurt you. In real life this often is not much (in fact it is often just the confidence to stand up to them).