I think you're misunderstanding my point really - which may be on me for my explanation, or on you for reading with preconceptions - whatever
Anyway...
That down block - yeah, sure, there's
an explanation for it. There's a movement, and a chamber position, and a transition in and out of position.
It's the teacher's job to show you the movement and give you a possible application ("this is to block a snap kick").
I firmly believe it's not the teacher's job to explain why the chamber is there or it's purpose (other than "preparatory position"). Or what you can do with the lead in and lead out. Or what else you can use that "block" motion/position for.
They should be able to help you find your answers to those questions, but any answer they just hand you is no answer at all.
Memorisation comes from instruction and repetition. Learning comes from discovery.
This specific part **So, physical issues aside, the "what works for you doesn't work for someone else" is not true in forms** is only correct if your sole purpose of doing a form is to learn the form...
Case in point - I can perform a takedown using what is presented in a pattern as a "punch followed by a turn into a low block". I'm using the same movements and the same transition. Present that as an alternative application to a 9th kup instead of "punch, block" and it'll only serve to confuse. It doesn't mean they need to practice the form more, it means they need to evolve their understanding of what is possible.