In what way are the symptoms not consistent with anatomy and physiology? Inconsistency with disease applies to FND but not to MECFS as far as I can see.

Or if they don't die they live in a state of extreme endurance which can be prevented by not overdoing it drastically and ignoring symptome.

Is there not just a single experience of energy? What would perceived energy expenditure be that is not also actual energy expenditure? Everybody has finite energy, people with long covid/MECFS have a much lower threshold +other symptoms, fatigue is just not something science can currently measure.

Some statements in eTable1 are unsafe for all patients and unjustified-that symptoms are independent of activity, that symptom decrease is not the goal of treatment, that the feeling of more or less energy is not a trusted tool in deciding on pleasurable activities.

I agree it possibly is a dysfunction of stress systems but there are still only a small minority of sufferers who focus too much on their symptoms/are too frightened by them so this approach is not appropriate for most, for the rest whether the activity is pleasurable or not makes no difference.