That's because the practitioners are mostly quacks who know little of
the workings of a human mind.
The DSM is just a method for ensuring that the conditions in vogue are
considered to be diseases and therefore, fall under in-plan.
"By design, the DSM is primarily concerned with the signs and symptoms
of mental disorders, rather than the underlying causes. It claims to
collect them together based on statistical or clinical patterns. As
such, it has been compared to a naturalist?s field guide to birds, with
similar advantages and disadvantages."