Physicians do not take a course in policy and politics. That is not a "core course." Also, a physicians course in pathophysiology is much more detailed than that offered in an advanced nursing course. But my question to you is, why do you think it is unnecessary for a psychiatrist to study and rotate through endocrinology, cardiology, and surgery etc.? Do you realize that some medical illness are present as a psychiatric illness? What if the psychiatrist only knew psychiatry and was treating psychiatric symptoms of a patient who actually had a medical condition? You can't provide care to patients independently without the knowledge of a physician.