The labels are very often useful for psychologists and psychiatrists to lower their own anxiety related to not knowing. Diagnosis gives us the feeling that we comprehend the patient thanks to putting them into a box of criterium. A series of indications related to the treatment and medication are supposed to make our lives easier.
It is a mistake to think that a diagnoses are fixed labels; the diagnosis should be dynamic - open to changes along the therapeutic process; the diagnosis is a continuum where we situate a patient on an axis between two extremes, which they may approach but very rarely reach completely.
The diagnosis is never clean. The majority of the patients can be situated between various diagnoses or they can present a comorbid diagnosis of the diosorders that tend to occur together.
The diagnosis can only give us some hints about the causes and the treatment as each human being is very different.