A legacy of the Flexner report of 1910, where Rockefeller/Carnegie had their say in which medical schools would continue to practice, and only if they conformed to the drug/surgery model of disease treatment: this effectively closed down the alternative schools such as Naturopathy and Homeopathy.
Mindsets rarely change if profit is the main motive for remaining in business: ie the cancer industry for one.
Nutritional Medicine or Orthomolecular Medicine is slowly gaining ground with many Medical Doctors joining its ranks.