Excellent - thanks for responding to this so positively. I wouldn't say you're necessarily trolling, rather than just arguing a little more forcefully than someone else might.

Almost all the remaining unexplained human ailments can be explained as disorders of the endocrine system.

I basically think that this is the absurd conclusion that demonstrates your chain of reasoning to be false. This is far wronger than the idea that Fibromyalgia could have an endocrine cause. And I think you've identified this problem with your argument even more acutely that I had.

I think there are a lot of useful ways you can reason from here, such as: 1 - It has never been the case previously that almost all unexplained human ailments have shared a single simple explanation 2 - Many conditions that we discovered a long time ago had simpler 'single pathogen' explanations, whereas many newer ones are quite complex. 3 - Although many of these conditions will eventually be explained, the explanations are not likely to be visible to a non-expert. 4 - If they all shared an explanation, there's no major reason why it should lie in the endocrine system. An alternative 'catch-all' explanation for these would be 'psycho-neuro-immunology', another somewhat overambitious school of mostly scientific thinking that could potentially claim these conditions more credibly.

My alternative explanation that collects this thinking is that most 'unexplained human ailments' are likely to be multifactorial. This is also the common wisdom. As to where to read and learn about this, by far the best place is www.uptodate.com. This is very popular but also potentially expensive. So if you really must, you could instead look through medical textbooks like Harrison's or Kumar and Clarke, focussing specifically on unexplained conditions. I would warn that reading about conditions unexplained by medical science via textbooks of medical science might be a bit like pulling teeth, but truly it should be one way to abstract away the knowledge of these conditions.

Another approach might be to learn more about the scores of "medically unexplained physical symptoms", "diagnoses of exclusion" and "functional disorders". Likewise some "functional symptoms" and some "ideopathic" or "cryptogenic" conditions. "functional", "ideopathic" and "cryptogenic" can be used interchangeably here, as in the sentence "we can't explain your problem, but as a concession, let's meet halfway and conceal our ignorance with this Latinate (or Greek) name. On my hypothesis, most such conditions will be about halfway heritable (as are most traits in behavioural genetics). They'll be correlated with each other, and with mental health conditions. They'll often be helped by SSRIs and by psychotherapy.

I guess you just have to learn a lot about these conditions with an open mind and see where you end up. If you gain a detailed knowledge and still think that some have an endocrine explanation, then write up your findings in a google doc, send it around to some other smart people who share that knowledge, and see what they say.