Are fundamentals a myth? No. But fundamentals are a myth depending on what they are. That said, they need defining. A fundamental should be that which is absolutely necessary, and done so as efficiently as possible.
I won't describe what those are, but it's safe to say whatever it takes to hit the CB in the exact spot needed on the correct line of aim with the appropriate speed. That's it. Swoop stroke, side arm, head movement...whatever. It doesn't matter. If that tip is hitting the CB where the shooter wants, that's what matters. Nothing else.
The key word is efficient. The text book type stroke, stance, grip etcetera are meant to help a shooter do what was described above (hit the CB properly) as efficiently as possible. That is accomplished through simplifying the motions, stances, grips as much as possible to that which is needed, and nothing more.
In other words, no superfluous or unnecessary body movements. Weird body movements while stroking the ball, following through, bizarre preshot routines....they may not harm anything, but they certainly don't help. They are excessive. Not only that, but the text book perfect stance and stroke is also less error-prone.
Now, for the individual shooter - they may be doing something for themselves by doing these things.. Might be something they do to get some kind of pre-shot "feel" ...or it's just a habit they could never shake but learned to deal with or make work, or maybe some stance that looks mechanically flawed is actually more comfortable to them? Hard to say.
The one thing I can say is, the proof is in the pudding. The CUE BALL DOESN'T LIE.
Look at a player like Keith McCready. He's my favorite example. Always loved his game. What an awful looking stroke and kind of weird stance. His follow through looks absolutely terrible. Almost like some bar player jumping up on a shot while they rush to shoot.
However, who here can say it doesn't work? That man has played some of the best 9-ball of all time. Great shot making, excellent position play. The whole package. Compare that to someone who has one of the most beautiful strokes of all time - Buddy Hall. Straight as can be. Methodical. Steady looking. Like a machine. No one I've ever seen before or after delivers the cue through the stroke like Buddy did. However, both these greats got the job done...with radically different styles...
How about some of the Filipinos? A whole thread could be dedicated to them.
Some might say that while some shooters have unique movements in their arm or stroke, there are fundamentals they all abide by. One of which that is often cited is - head movement. No matter what they all do, at the moment of impact - they have a steady head. Wrong! Some have slight head movement. Some slight shoulder movement. Some have minor movement in the bridge arm and hand. Some do twisting motions with their grip hand. I've seen it all. For all the talk about pros doing it right, there are many of them violating many of the rules taught to beginners as "fundamentals" ...and running rack after rack doing so. I know, because I was fanatical at studying the perfect stroke and mechanics, but would spend hours and hours at Florida Tour stops and other pro events watching the mechanics of these guys and scratch my head.
Up to this point, I have seen every single fundamental broken and violated by players who shoot great. Except for one: They all hit the CB where they want, with the right speed and on the right line of aim.
Now, this doesn't mean we all should just do whatever we want and it will work out for us like it did some of these players. That's a bad, bad idea gentlemen. These players with what appears to be gross violation of the most accepted fundamentals and who play top level are the EXCEPTION. Most pros are fine examples of perfect fundamentals applied.
For every one of these fundamental breakers, there are tens of thousands, if not more, of players who are being held back from maximizing their potential because of bad fundamentals and flaws. That's why getting quality lessons from quality instructors pays off for 9/10 students or more. They benefit from following these stance, grip, stroke fundamentals.
In other sports, such as golf, tennis, football etcetera...professional coaches and trainers won't tell you to just do whatever works for you. In those sports and in those industries, it is strongly held and believed that there is a mechanically superior form or technique.
Yes, there's more than one way to skin a cat. However, at any one given point in time, there's only one most efficient way. The way that gets the job done with the least amount of effort, energy and possibility for error. That's what the pool instructors teach.
The idea is, when your body and mind are not burdened as much, that's just a tiny bit more of one's self that can be put toward concentrating on the task. Or, say a certain kind of grip causes you to use 3% more muscle energy and mind/muscle control to use because it is a more complex movement that requires more signals from the brain to muscles to correct or keep on path. Then that is not most efficient. Burning "resources" doing something the harder way. Which means, the maximum potential is not being realized.
The best path is going with the textbook perfect stroke, grip and stance that is taught. It's the most efficient that we know of today. It's also a cookie-cutter method. Designed to help the vast majority of players reach their greatest potential. That said, it is impossible to teach any kind of grip, stance or stroke style to suit some individuals unique needs. Which are entirely personal to them. Whether it is mental, physical or just has to do with that hard to quantify and define "feel" ...
What I mean by that is, those people who do things in an unorthodox way, they probably do so because for whatever reason, the textbook way didn't work for them. Some would disagree, and say that the unorthodox guy would be better shooting text book....
Would they? Would someone like Keith be even better than he was with a Buddy style stroke and mechanics? If you asked pro golf trainers and football trainers, they would say yes. They would say yes without hesitation.
I personally don't agree. I like to believe there's always something unique and special about some people. And that some things truly do work better for others. This is merely a belief, and I acknowledge it has no scientific backing. It's a matter of faith for me. I just like to think so.
However, those who have studied it to the extreme - who have millions and millions of dollars invested in it all say yes, they would be better if they did things the right way. Good example is all the talk about Tim Tebow. He has an unorthodox throw. It worked fine, but it's potential is limited. Doesn't get the job done in the NFL, worked in college though. So they are rebuilding his throw, to throw the perfect way. Like Brady or others.
In those sports, they strongly promote the pro way of doing things. Doesn't mean they are right, but usually those with so much money riding on it - tend not to be wasting their money.
In pool, we don't have nearly the cut throat kind of vetting process as these sports...but it's pretty clear that the guys with the eccentric strokes, grips and stances tend to remain in the realm of league players, and the guys (or gals) with near perfect fundamentals can reach A player levels or even semi-pro.