> CFS was my brother's diagnosis, until it became lyme.
A family member of mine was diagnosed with CFS and it was like the doctors she talked to were stuck in decade-old views of psychology. It was psychosomatic and as a result there wasn't much help she could get. Never mind that she went from one of the most (hyper-)active, traveling, bubbly people to being stuck in a wheelchair and sleeping much of the time; because it was in her head these very real effects somehow... weren't real enough.
The first and most obvious issue, in my view, is that even if CFS is 'just between your ears', then that's still no less real of an issue and it is not helped by dismissal.
The second issue that I hadn't really considered until your comment, and one that might be even more serious, is that this dismissal might actually prevent specialists from proper diagnosis.
After a decade (or maybe even two, I don't even remember anymore) of low-energy existence, living on a pittance, having only the luck that many of her old students and friends kept taking care of her, after all that she went to some clinic somewhere in Asia (Singapore, I think) and while I'm not sure what the diagnosis was, it was apparently something relatively known (something related to vaccines she had before visiting Vietnam), treatable, and she was back to her old self in no time (a decade-or-so older, though).
I'm wondering if more effort might have been made, and a solution found much sooner, had it not been so easy to dismiss her issues as 'psychosomatic'.