This is not to say that all trainers are physical wrecks and that all boxers are idiots. A trainer with increased physical prowess may be a better trainer, and a boxer with increased mental prowess may be a better boxer. A great trainer may be an Olympic champion, and an Olympic boxer may be a genius. However, in general, trainers do not need much physical prowess and boxers do not need a lot of mental prowess. Look at professional sports. Some great trainers can perform physically, but many are physical wrecks, and some great athletes are bright, but many are dim.
The trainer/boxer comparison may also be compared to the martial art instructor and the martial art student. A great instructor needs the mental skills needed to train students, but needs few physical skills. A great student needs the physical skills needed perform techniques, but only needs minimal mental skills. An idiot will not make a good instructor, and a person who cannot perform physically will not make a good martial artist. Most people will agree that an idiot will not make a good instructor, but, to be politically correct, they will probably disagree that a person with limited physical abilities will not be a good martial artist. The current “correct” belief is that all persons can be good at anything if they are given the opportunity. “Given the opportunity” usually means lowering the requirements for something until any person can do it.
The martial arts are combat arts. They were created from a need to prevent the enemy from injuring or killing you, and from a need for you to be able to injure or kill the enemy. The other benefits that may be gained from performing martial arts may be a good reason to perform them, but if you cannot physically stop an attacker from injuring or killing you and you are not able to injure or kill the enemy, you will never be a true martial artist. To believe otherwise will mislead mentally or physically limited students into believing they may be effective martial artists. Although, with training that is tailored to fit their limitations, they maybe more able to defend themselves, they will probably never become true martial artists. If you give black belts to students who cannot perform techniques required of all other black belts or you lower the standards required of black belts, then you degrade the status of the black belt and mislead the students.