I was always a bit confused by the "doctors don't want you to know about" line until I understood that it's in a rather US-centric cultural context where doctors are seen as just wanting your money. Though there's probably also the idea that practitioners of mainstream Western medicine are hostile to "alternative" remedies and don't want you to try the latter even assuming that they're actually effective.

I suppose that, ironically, well-intentioned doctors would indeed prefer that people not know about these "tricks" and other medical scams.