As far as I can tell from websites, that program is just to report to the state what people are taking so that people who get multiple prescriptions of the same controlled substance can be caught. The purpose of a controlled substance is to limit a prescription to what a doctor feels is safe for that patient. There does not seem to be a limit imposed. The only change would be to add a prescription drug to the controlled substance list. This would then impose additional work on a physician, thus maybe making it more compelling for a physician to just stop prescribing it. That is speculation so you would need to ask your doctor about the specifics of what they are saying and why they made the decision to cut Xanax to find out what they are thinking.