There's another reason that this general mindset exists: think drug interactions are poorly understood? Try researching nutrition and food interactions.
People eat thousands of chemicals daily, and we still haven't figured out if something as superficially simple as, e.g., the "food pyramid" is a good thing or not. What you eat is massively more complex than the drugs you are prescribed. The biggest difference there is that (most of) the chemicals have been around and in our diet for quite a long time, so they're evidently not (very) dangerous (to most. see also Celiac / Coeliac disease for an example of how long problems can exist)
Holistic approaches may be good; they may even be the best approach. But due to the insane amount of variables, they're also about the furthest from science as it's possible to get, and the least actionable in a specific sense. Everyone knows they should "eat better". Well... define "better". And be sure it applies to everyone, or be able to know who to apply what advice to.
People eat thousands of chemicals daily, and we still haven't figured out if something as superficially simple as, e.g., the "food pyramid" is a good thing or not. What you eat is massively more complex than the drugs you are prescribed. The biggest difference there is that (most of) the chemicals have been around and in our diet for quite a long time, so they're evidently not (very) dangerous (to most. see also Celiac / Coeliac disease for an example of how long problems can exist)
Holistic approaches may be good; they may even be the best approach. But due to the insane amount of variables, they're also about the furthest from science as it's possible to get, and the least actionable in a specific sense. Everyone knows they should "eat better". Well... define "better". And be sure it applies to everyone, or be able to know who to apply what advice to.