No, it's that I know that extremely few players ever take lessons. For some, it's because of the cost, but for most, it's simply that improving at pool is not very important to them and that they aren't willing to invest any significant amount of time to it.
To the 1%, and that might even be too high, that are willing to invest a significant amount of time and money to improvement, nearly all of them will manage to correct some, if not all, of their stroke flaws.
Thanks for taking the time to clarify.