All self-defense methodologies are systems that are intended to "solve your threat problem". Lots of these systems are systemically flawed, but they still work in many situations. The key word here is many.
For example, ignoring all threats and/or denying the existence of danger is a methodology many people practice. And for a percentage of them, this method works. They live and die and they are never assaulted or victims of crime. This method is systemically flawed, yet it still works for many people.
But what is more common is for students to become believers in a system that is systemically flawed. Despite this flaw, this system will "work" in certain circumstances. Three Mile Island had a systemic safety flaw, yet for many years this flaw did not stop it's ability to generate energy. The circumstances that expose a flaw may never arise. Thus, providing false evidence that the system is in fact "flawless".
A systemic flaw in many self-defense systems (particularly for women) is that they provide the student with a sense of having the ability to handle any and all physical threats with physical "fighting" techniques. As a result, this person projects a real sense of confidence and employs boundary setting that actually deters asocial predatory assailants looking for week and submissive victims. The student's fighting ability maybe an illusion, but the ensuing confidence and resulting deterrence is real.
Therefore, a systemically flawed self-defense still "works" in the same way Three Mile Island worked fine for many years. My question for self-defense instructors is "Are you introducing a systemic flaw into your system as a means to give your students the confidence to set personal boundaries and deter predators?" And if the answer is yes, "Shouldn't you figure out a better way?"