Ok, here's proof of axial length changing following application of the method for years:
There was a member on the forums who was measuring his axial elongation while at the same time applying the reduced lens method. His result is shown in the following plot.[0] It is a significant improvement that can't be ignored, and can't be explained by day to day fluctuations or measurement error. So we know that at least some level of axial elongation can be reversed, and the idea is not complete quackery.
Also the reduced lens method has nothing to do with the Bates method, or undercorrection that leads to blur adaptation.
> "The only scientifically proven intervention for reducing myopia is surgery"
Which surgery reduces myopia? If you're thinking of LASIK then it doesn't change axial elongation.