what weakness has been identified with using a sole categorical approach to diagnosing personality disorders?

Categorical diagnoses are based on arbitrary diagnosis thresholds and use an all-or-nothing classification

Explanation:

In order to use Sole categorical approach to diagnose personality disorders, the psychologists are required to fill a set of cheek box about the characteristics displayed by the patient.

The problem is that this process will be heavily influenced by the psychologists' personal judgement along with social and cultural context that might influence the patient. The combination of all the things above make the diagnosis become unreliable.