If a McDojo says they teach self-defense, there is no legal definition of what that is. If I tell someone they can block a punch by raising their arm, and I say that's self-defense, who can legally prove it isn't?based on the legal definition of "self defense" (which varies depending on where you live) you can very much determine what is effective teaching and what isn't. What you are referring to is the "use of force" part of self defense which, I agree, what's effective and what isn't is very subjective and variable. But if you just teach people how to fight and never teach the legality of their actions is it really self defense or just fighting? If a self defense instructor says you can just punch someone who verbally threatens to hurt you but you live in the UK where self defense is defined by the actual actions of the other person and not verbal aggression then they are not teaching self defense and could be potentially putting their client at risk of legal consequences or criminal charges. However in places like Michigan for example, a verbal threat does constitute a legitimate threat and a person can legally physically act on it by punching the aggressor in the face. For sure there is no definitive "best" physical self defense method but that is not the same as saying you can't measure the legitimacy of instruction.
Yes it absolutely 100% is. Self defense is a legal term. What constitutes self defense varies by country and in the US by state. In the US the legal definition is unanimous across the states up to one specific point: Self defense in the US is legally defined as "the right to prevent suffering force or violence through the use of a sufficient level of counteracting force or violence." The specific point that is regulated state to state in the US is the word "sufficient". Fore example in Florida the stand your ground laws allows somebody to proactively use force to stop a threat even outside of their own property. This means that you can be the first one to cause physical violence to another and it can still be classified as self defense provided they made a threat to you in some way first. In Michigan you can meet a threat with force even if you can safely leave without any use of force. However in states such as Arkansas where every person has a duty to retreat meaning that you have to do everything to leave or deescalate the situation before you are allowed to act (exception: Castle Doctrine), using force in anyway without first trying to leave or deescalate is a crime. So if someone in Connecticut for example is claiming to teach self defense but only teach you how to fight and a person starts yelling at you and shoves you and your response is to hit them because that's what you were taught was self defense then you are just as guilty of assault as the other person because you were not taught actual self defense as described by the law in that region.
And if I really wanted to follow that path, I'd say that 90% of the garbage I see 'real' dojos teaching as an upper body block is trash. I can destroy those blocks with the tiniest bit of pressure. So are they not teaching self-defense either? Shut them all down! Hey, if it's up to me to say what's self-defense and what isn't, I'm not going to be very popular when I shut down nearly every martial arts studio.
McDojo arts aren't very good. I certainly would not train at one. But the people who do clearly aren't there to learn good solid martial arts. They are getting what they paid for.