I think it's more the common language of pseudoscience than it is the language of psychiatry. There are many schools of thought and disciplines within psychiatry, even when it comes to the clinical psychology of illness. The logic behind the psychosocial model of ME is about the same as with astrology: stars and planets exist, therefore surely they influence us. Replace "stars and planets" with "the brain" and you have roughly the same belief system. The entire mechanism is hidden in the mystery step 2, where something happens that can't be shown or confirmed but this step is glossed over by creating a magic leap between steps 1 and 3. Good psychiatrists do not rely on a magical step 2. That would be most of them. It takes mediocre minds to build anything out of such a model, whether they are licensed physicians or sell rhino horn boner pills.