so can the feds
Well, these days they can do anything they want it would seem. But you know that is not what was intended. In the 1920s it was thought that a Constitutional Amendment was necessary to ban the sale of alcohol. If you can explain the Constitutional difference between alcohol and drugs you will be the first to do so.
Once prohibition was repealed some States and localities banned alcohol sales on their own, just as I have absurdly suggested might be done for drugs.
ML/NJ