In the martial arts community, even to this day, there are still quite a lot of phonies out there, unfortunately. You'd think with the advent of the UFC and MMA people finally figured out what works and what doesn't.
Unfortunately, that's not necessarily the case and there are still many charlatans involved in martial arts out there, particularly in the traditional martial arts and self-defense community.
Even in MMA, there are good instructors and bad instructors, but nowhere near to the same level seen in the traditional martial arts world.
In the following video, we see a bizarre demonstration by an alleged self-defense instructor showing moves that would never work and is pretty much just bullying his subject around.
First of all, he is going way too rough, twisting, and contorting his much smaller and weaker subject's body in a way that could very well result in injury. This is especially true when you look at the way this 'instructor' is twisting around the poor kid's neck and his shoulder joint.
Towards the end of the video, this demonstration gets even weirder when the instructor bends his subject over a table and grabs his crotch area from behind. Perhaps the instructor had ulterior motives with this 'demonstration' but whatever the case there is no way any of these moves he is showing would actually be effective against someone who is resisting in any way.
This video, though an extreme and bizarre example, is a good instance of the problem with traditional martial arts in general where one person does the move and the other person simply takes it without offering any sort of resistance.
In real martial arts such as Brazilian jiu-jitsu or boxing, if the technique doesn't work against someone who is fully resisting in sparring, it is not an effective maneuver.