This is worsened by many people doing a poor job of providing said feedback, for a myriad of reasons: because they never learned how, because they were never in an environment conducive to doing so, because they flat-out just don't care, etc.
Not to mention, there's also the fact that some pills are just straight-up hard to swallow. I've had to choke down more than a few of those, and it took a long time for me to develop the maturity to do so productively.
An NDA doesn't fix any of these problems.
Absolutely! I've successfully built and run such training.
Most things are trainable skills. For example, I'll never be able to run as fast as Usain Bolt, not by a country mile. But, if I develop my running skills to their maximum potential, I'll be able to outpace a pretty good chunk of the rest of the population.
Same goes for communications, programming, whatever. You might not have what it takes to be The Best In The World, but most people definitely have the potential to become unreasonably competent at a thing, should they choose to put in the work.