The culture of biomedicine emphasizes the importance of anatomy and physiology when looking for ways to treat diseases and illnesses in our society. Knowing the physiological as well as anatomical differences between male and female bodies can aid in our means of treating each sex effectively.
My way of defining a dichotomy would be the idea of two things that are somewhat, almost, or entirely opposite to one another. I do believe these kinds of contrasts exist because, in terms of male vs. female, there are different structures, needs, and patterns of behavior between the two sexes.
In the U.S., as well as other countries around the world, there is a strong social pressure on men and women to be opposite in terms of nearly everything including behavior, clothing, body type, etc. However this alone is possibly detrimental to mental health of some patients. Rather, instead of misleading stereotypes, what we need to focus on is anatomical variations between the two sexes in order to treat each patient professionally and effectively.
So in some cases, yes, the dichotomy is logical, such as when one would be focusing on the anatomical and physiological differences between men and women. However, in other cases it may be ineffective to people who choose not to identify as male or female in terms of gender.