There was a dogfight in that instance, where defenders tried to intercept attackers. That's how it normally works. That's how almost every fight I've been in goes, beside MA furballs- all of the good, realistic, group on group engagements I've been on happen because of attackers being intercepted by defenders.
Dog fighters do have an impact on the war- they kill attackers.
Remember, fighters, by definition, are defensive weapons. There is no reason for fighters to exist other than to kill attacking aircraft.
That's one of the reasons Germany lost the war- Hitler didn't like fighters, he liked bombers- he saw fighters as defensive weapons, and he wanted to focus on the offense. This is why he insisted that the Me262 be designed primarily as a bomber, which greatly delayed its arrival to the front as an interceptor, as a defensive weapon, as a 'cowards tool'.