I think this is pretty obviously untrue. For one thing, to be pedantic, if one person is trying to get away (i.e., doesn't want to be there), that's not normally called a 'fight', it's an attack, which isn't the same thing (and would require different strategies as well).
In any case, if nobody really wanted to be in a fight, there wouldn't be so many fights. This is especially true when people start talking about 'street fights' and 'bar fights', which seem to be pretty much entirely avoidable, and easily so, with very few exceptions.
Personally, I'm not going to waste my time trying to figure out how to win a 'bar fight'. Don't go to places there are likely to be bar fights, don't stay in a place where there are people who seem 'off' in any way, and don't get in arguments with crazy people. Voila, problem solved.
Muggings and the like are a far more interesting problem.
This raises a good point that I have been thinking about a lot lately. I am a bouncer. I am NOT paid to fight. I would be fired if I fought with someone. I am paid to stop other people fighting and i am paid to stop people who are attacking other people. It can be a fine distinction, but it is often an important one. In my opinion, a fight is two people agreeing in the moment to try to injure each other for whatever dumbassed reason, mutual combat. An attack is one person trying to injure another person without the attackee's consent. Different scenarios, different responses from me.
I have found that there are often three phases in a fight. I call them fussin', fightin', and fuckin'. I have the best shot of surviving stopping that fight if I intervene in either the fussin' or the fuckin' phases. In fussin', folks are working out a contract to fight. If I interrupt that negotiation, I can remind them about jail, the shame of getting pwned by an old fat lady, the loss of the price of admission, etc. It can work. But if I am late or unsuccessful, they start fightin'. I dont want any part of that shit, flying fists, beer bottles, possible weapons, screw that. Time to call my coworkers over. Because after a few seconds of fists, they clinch and start rolling around on the ground fuckin'. Fun to watch, but now is the safe time to get these people out of the venue. They are way too interested in the other man on top of them to pay much attention to the crew coming up to choke, I mean Lateral Vascular Neck Restraint (That's Cop-ese for hadakajime which is Japanese for would you like to take a nap now thanks) them right out, cuff them, and haul them out of the building. That's why there are so many youtube videos about "Why dont the fat donut eating cop wannabe's DO something!?!?!?!?!!?" Both people want to duke it out, they wont be talked down, they haven't done anything actionable yet, oh wait now they have and I am NOT getting in the middle of those two dogs fornicating. Wait, wait, now. Find the safe place, let the technique develop. Good aikido.
I dont like dealing with attacks as much. Attacks are not mutual, unpredictable, and someone is getting screwed without their consent. Pisses me off, and I dont do good aikido when I am pissed off. Attacks usually call for more immediate action, I am usually alone of with one other person, and attackers are usually more motivated to do real harm than mutual combatants. They have a purpose, and it is bad. If someone is being attacked, I am scared, but I feel an ethical imperative to intervene as best as I can. Get backup now, get the victim out of there, incapacitate the attacker and get them into the hands of the police ASAP.
I dont fight. It is stupid. I am ocassionally attacked, only once seriously (the weapon's presence made the attack serious more than the wielder's intent), and I had the space to deal verbally with that one. The attacks require swift response. If the attack is serious and I have no space, my response will be complete survival. Fuck them, fuck ethics, fuck aikido, fuck their TAPOUT tshirt, fuck common courtesy, I'm going to bite their esophagus out.
"Your Honor, I was afraid for my life, I had no idea what my attacker wanted, knew, or was carrying. I was just afraid for my life. I responded out of pure fear."