> Sure. But we know they are important. Despite being “single molecules.”
The point is that there's huge debate on how they work, why they work, whether they work for this and that, etc, despite them being about as tiny and simple in form as you could ask for.
And as far as I know no one has ever claimed that Vitamin C and D are not single molecules, so I've no idea why you put that in quotes. It's relevant that they're not, for example, the mixture of hundreds or even thousands of synergistic and antagonistic compounds, in various quantities, found in every single plant.
> Because they appear unsubstantiated. You’re describing treatments. That’s a different ball game.
Taking C for a cold, or D in winter, is NOT unsubstantiated - there are studies that show effect, and studies that show no effect. It's debated. That's exactly my point, that even these simple and tiny molecules inspire massive confusion and debate. It's in no way like an engine. The body and how it processes things like vitamins is so, so much more complex.
You can say this same thing about thousands of molecules and simple substances, which the scientismic community stands behind despite huge debate - SSRIs, anti-psychotics, glyphosate, etc. We don't understand them, and vested interests in white coats want us to believe otherwise. Remember tobacco being promoted by doctors? It wasn't that long ago.
The point, again, is this: that if we can have so much uncertainty about such tiny and simple things, why would we believe it's safe to muck about with our food supply (GMO monocultures), or to declare glyphosate safe and cover the planet with it, or claim that mRNA vaccines are utterly harmless (despite immediate evidence to the contrary, as now proven beyond doubt). Remember CFCs, PFAS, thalidomide?
These things are fundamentally different from your example of a simple combustion engine. They're complex on a level far beyond our current ability to comprehend. Even if we think we know what's going on, we really, really don't. We have hints, we have hunches, we have incomplete models with giant and dangerous holes in.