Maybe I have this wrong, but isn't it true that if you are cured by, say, gluten avoidance, then you didn't actually have me/cfs, but undiagnosed gluten allergy/intolerance?
Something is only a "cure" for ME/CFS if it cures most of the patients, right? And we've found nothing that comes even close, as far as I know.
I'm fairly confident that there are many people with me/cfs diagnoses that actually have some other known, but undiagnosed illness. For all I know, I'm one of them.
On the other hand, there's no doubt that we all have a lot of problems with multiple body systems and symptomatic treatment can improve our condition to some degree. They're just not cures.