What's important though is that we don't know which system is the main culprit of a disease. It may be a psychological factor but it might as well be a physical factor, but with new diseases we cannot tell which one and assuming that it's mainly psychological can be quite dangerous.
That does seem to be an important point and certainly some gray area.
A friend swears that it was trauma that did it for her, for myself, a bad gut bug sent me spiraling. My Harvard teaching brother says that the role of environmental toxins are to blame in epigenetic shifting (he is a published researcher). I do find it interesting that toxins are seldom discussed in ME or autoimmune circles.