While things like diet and massage therapy don't do a damned thing to directly affect any disease process, they can help a patient undergoing difficult and often painful treatment a sense of greater well being and in that case, they are worth prescribing and getting them paid for by insurance.

Bottom line, they're useful as adjuncts.

The problem only arises when some arrogant jackass tries to market pseudoscience as a first line treatment. Those are the people who need to be stopped.