Like, for example the abnormal EEGs associated with some affective disorders, the ways some drugs can cause clinical depression or greatly exacerbate it, or the remarkable responses (reported, often, not by the patient but by the family, friends, and associates of the patient) to some medications?
Or, on a larger scale, Are all opinions determined not by evidence but by the desire for some kind of gain? And if so, is the opinion that opinions are so determined itself so determined? Certainly the opinion that opinions are determined by economic gain and power would fallunder the genral classification of "Marxism", and while there are many problems with Marxism, the first is the problem of how does Marxism explain Karl Marx?
And what is "Psychiatry" that "it" can adopt or reject models?
Having said all that, I will eagerly agree that medical insurance companies sure wish that all psychiatric problems would respond to medications which are often cheaper (and more effective, maybe) than "the talking cure".
Well, as a psychiatrist (ret) I would use "pursue" instead of adopt. You raise legitimate points and psychiatry has the data you mention and is doing that type of research you mention. It is also abandoning "talking therapy," (too time-consuming) and making unwarranted diagnoses all for the sake of increasing the bottom line. For example, Personality disorders are rarely diagnosed and are replaced with bi-polar affective disorder--why? Because you cannot treat personality disorders with medicine. Virtually all of the research in Psychiatry pursues the "Nature" (biological) side of mental illness while ignoring the "Nurture" (life's experiences and learning) side---that in and of itself is pursuit of the biological model.