My (unsupported) hypothesis is that the causative agents behind
chronic idiopathic illnesses obey a power law: that there should be one treatment that will help an extremely large percentage of people (greater than 30%, say) that should be a "first-line idiopathic treatment regime", and then another treatment that covers another 10%, and then a rapid decline into a long tail of interventions that will only help a few percent of people each.
I say this because the causes of idiopathic diseases, when revealed, seem to be similar in structure to the causes of idiopathically failing companies, or idiopathically broken computers, or idiopathically recidivist criminals: namely, that there is some obvious-after-the-fact property of the environment, which combines with a person who never learned how to deal with/be hygienic in the case of/avoid that property. Computers choke on dust; criminals have friends/family who are in debt and need money; companies hire workers based on status rather than efficacy. None of the subjects of these forces realize that they need to do something about them (clean the computer; get their family to declare bankruptcy; give objective tests to their workers), so they get worse and worse until someone who actually knows enough about their life, while also not being immersed in the subculture that is missing the hygienic knowledge, comes along and helps them.
For the case of criminals (and bad parents), this is the job of social workers. For dentistry, you've got dental hygienists. But who is supposed to teach people how to avoid fungal infections, if it's not part of their implicit cultural package of knowledge? Who's supposed to teach them why they should care about the effects of their diet on their blood pressure, if hey have no family history of hypertension? Etc.
And because of that gap in cultural hygiene-knowledge transmission, I have a strong feeling that a few interventions that directly target the knowledge gaps equivalent to "have you tried blowing compressed air into the computer's vent?" Would have an extremely outsized impact in these cases.