and other people cant fix cars no matter who instructs them and for how long.
most things have an immediate feedback loop, if you can't tell your brakes don't work when you drive the car then that's a significant cognitive defect in you, if you concluded your supposed to drive round with no brakes for two weeks while gravity worked it magic, then you have far greater problems to work on. that's not at all failure of people's ability to learn things without formal instruction, that's you not being capable of working a box of matches
fighting like fixing cars has an immediate feedback loop, ''that hurt, won't do that again'' '', that hurt him, do that again''
its also more than possible to pick up good technique by watching others, even watching boxing or mma is showing good technique that you can then develop by trial and error
which is really only a slightly altered version of someone demonstrating a technique in formal training and you going off to practice
formal training has distinked limits, you cant get more out than their natural talent will allow, thats general why talented children become talented adults.
if your putting forward that there are people who have spent years being instructed in martial arts that cant fight their way out of a paper bag, then i agree. if you saying that no one who trains TMA can fight then your very very wrong
nb its very rare , if you do it correctly, that you need to bleed brakes after changing the pads, that didn't need bleeding before hand, it does take a short while to bed the brakes in, perhaps that what confused you. or you were just doing the whole thing wrong