And it should be my right to buy snake oil, just as it is my right to pay hundreds of thousands of dollars for Scientology courses.

You can buy snake oil. The limitation is you can't market it as curing cancer and doctor's can't prescribe it. Which is a vary important distinction.

Herbal infusions, Homeopity, and a host of other 'options' still, but if you call yourself a doctor and not just a 'faith healer' they effectively don't which is a good thing.