The Dodo Bird theory may, as it states, be relevant to therapy, but it holds no water for psychiatric treatment. Some mental disorders are known to respond radically differently to certain psychoactive medications. SSRIs are a canonical example. They are an effective treatment for major depression, but in bipolar disorder they cause rapid cycling and increase suicide risk.
Assuming mental disorders exist, sure. But there is also evidence that a sufficiently technocratic government will use psychoactive drugs indiscriminately on its population in order to coerce and control them [0][1][2][3]. We must demonstrate somehow that mental disorders not only exist, but that their classification is due to science, and not due to bigotry and a lack of understanding [4][5].
Your example of SSRIs is an especially poor one, as SSRIs are well-understood to have been developed by the pharmaceutical industry as part of a panpsychic wellness package which is meant to be sold pill-by-pill to the public [6][7]. SSRIs today are like sugar in the past [8], with a corporate army of compensated scientists ready to study the noise and find useful results from harmful chemicals.
