I'm confused about something. Forgive me if this is a dumb question, but if they acknowledge PEM as a core symptom, how does that even work with their understanding of the illness? If it's behavioral and false illness beliefs, how come that manifests as PEM in most patients? How come we even have similiar enough symptoms for this "illness" to have a name and specific traits, if it's just in our mind?
If you try to deconstruct this, you get no further than 'over-attention to normal physiological response to exercise' - pretty much.
Which is basically utterly ridiculous if you think about it for more than fourteen seconds.
Perhaps they've been busy and not had the time in the last couple of decades.
In short, they are saying normal feelings of tiredness, and delayed onset muscle soreness following exercise are the whole important spectrum of symptoms, and that the rest are 'somatic' symptoms like you get in depression. Combine this with muscle wasting to drive DOMS, and you're golden, perhaps throw in 'poor sleep hygiene' as an excuse for some of the tiredness if you're feeling ambitious.
Unfortunately, DOMS does not cause muscle pain in non-exercised muscle groups in the next several days. Or cause cognitive issues. Or ...
And the timescales are all wrong - you simply can't explain how you can do something one day, and then the next day the same thing will trigger PEM.
Never mind that nobody that's looked has actually found any deconditioning.
All other interpretations of the symptoms are handwaved away.