The WIND UP was at one time - taught. It (wind up) was a basic part of "pre" delivery that was incorportaed into the motion prior to the pitch itself. This phase was routinely instructed SEPERATE from the delivery motion itself.
Confusing.. of course. Why? Because very few .. if any pitching coaches, remember the purpose for that phase that was truely THE WIND UP.
The wind up is the initial PHASE of the delivery motion with no runners on - generally. And it's purpose was to accomplish a few things like to get the muscles moving again from the last delivery, initiate a bit of timiing to the pitcher's tempo, and to stretch the the muscles.. especially in the shoulders - arms - torso .. due to the repeated spurts of stress on the body .. pitch after pitch.
Some guys react well to the discipline .. when properly taught, others not so well. And with good reason. This training was second nature to coaches at the youth level during the 30's,40's and into the 50's. However, with advances in human dynamics and all sorts of "systems" on the market... coupled with the overall lack of interest in the game itself with the advent of other sports and a mix in cultural and economic factors.. the wind up along with other BASICS have gone the way of the dodo.. Not in all parts mind you... just most.
So, it's not surpirsing that a coach will want you to use the wind up... but it's also not surpirsing that he/she doesn't have the slightest idea what benefits are generated .. much less how to show you themselves. And might I add... trying to show you how to properly progress though the three (3) basic phases of a good wind up is almost impossible with the surface conditions on just about every pitcher's mound you'll find on public and private ball fields today. In fact, years ago a neighbor of mine said he bought a video called Pitching the MLB way... then another, and aonther ... but his kid still had all kinds of problems. Well, as I watched the videos ..as he asked... I remarked at how well maintained the mounds were that these pros were pitching off of. When I asked if his kid used the same quality of mounds, his answer was... "are you kidding!!??"
He sitill didn't get it.
So, I wish I had better news for you.. but the adivce of "stick it out and do the best you can", is not only advice.. it's a fact of life in youth baseball.