The article portrays a simple dichotomy: mental versus physical. But there is something interesting going on with psycho-social explanations. Given the epistemological difficulties one rather expects extended fights between the proponents of rival psycho-social theories. But the tendency is for one such theory to win and obliterate its rivals.
Consider ME/CFS. The human body has remarkable powers of recuperation. Feel ill with a cold? Just take two weeks off to rest and you will recover. Broken bone? That will need splinting, but again it will heal up in six weeks. Ah! Now we come to the difficulty. There are standard times, two weeks, six weeks; what happens if something goes wrong and healing takes a lot longer?
One psycho-social explanation of ME/CFS is that patients aren't patient. Something nasty has happened, bio-medically, and they need to take two year out of their hectic life to recover. After six months they cannot take resting and pacing any more and do too much, too soon, provoking a major relapse. That restarts the clock on two years to recover. Rinse and repeat indefinitely. Call that "trying too hard".
The rival psycho-social explanation is that patients are deconditioned due to too much rest and need to exercise and build up their stamina on a "normal" schedule. Call this "not trying hard enough". This doesn't really work as an explanation because some of the patients are ex-athletes and familiar with training and building back up systematically after time off for an injury or illness. They are going to the doctor because they have done what always worked in past, because it hasn't worked this time. The rival psycho-social explanation isn't relevant to the actual problem.
It is worse than that. NASA attempts to study the effects of weightless on the ground, in gravity, by having people lie in bed and get deconditioned. Deconditioning is a rather delicate effect. It depends on a rigid discipline of lying down all the time. The effects wear off rather quickly. Crucially the effect wears off monotonically. It is not like ME/CFS with its key symptom of Post-Exertional Malaise: sufferers think they are getting better, but a day or two later, wallop, they have a flare up of symptoms.
The natural expectation is for a fight between psychologists. "Trying to hard" versus "not trying hard enough". One expects it to be a one-sided fight. "not trying hard enough" is a much worse fit to what the patients experience.
Back in the real world "not trying hard enough" has won a total victory. When patients are angry about the "not trying hard enough" explanation, that is understood as anger about the psycho-social model, as if there were only one. The important question is "Why prefer the implausible psycho-social model over the plausible one?". And that question is difficult to ask.
The article manages to skip over the central issue with popular "all in your head" explanations. It is not that they compare unfavourably with "physical illness" explanations. The problem is that they compare unfavourably with less popular "all in your head" explanations. What is going on there?