If this was the case there would be facilities in remote countries with lax law making billions off of curing cancer. While there are indeed facilities in countries with lax laws doing questionable medicine, none are known for actually working. Instead they are known for preying on people. The fact that successful facilities don't exist indicates to me that your hypothesis is incorrect.

As I’ve pointed out elsewhere, I don’t think curing cancer is the bar for sober self-experimentation. “Noticeable amelioration of disease” is.

There is substantial regulatory burden that prevents US-based companies from doing what you suggest. In fact there is regulatory burden that prevents things that 99% of American voters would prefer, like having reciprocity agreements that allow you to take any drug that had already been approved in Europe. It’s instructive to look at the case of Halassy and notice how much reflexive resistance there is to even the most self-evidently good ideas.

To make things concrete, here’s a practical idea: write down everything you eat while on a medication and rate your subjective well being everyday. Look for patterns. If anything jumps out at you, try eliminating it and seeing if your subjective wellbeing improves. Is this method fool-proof and without failure modes? Of course not. Is the prior probability that you’re eating at least one thing that’s unknowingly contraindicated for your condition / treatment pair very low? Also no.

My model is that the rate limiting factor for spotting unknown contraindications mostly just individual attention / discipline, so EMH arguments are unresponsive to this factor.

Consider the following argument: if obesity were such a big health problem, why is everyone fat? Mostly because losing weight is really hard, which I sympathize with but don’t take as an indication that it’s impossible to do anything about it.

In fact we don’t even have to bring disease into it at all. I’m sure that if i did a systematic elimination diet i would find one or two common foods that really didn’t agree with me, which i could make noticeable differences in QoL by avoiding. Why don’t I? Mostly because I’m just too lazy, and I’m fine with copping to that. But i don’t think it’s crazy for someone to choose otherwise, especially if they had a higher upside.