The kids are not made to behave. They succeed in avoiding responsibility. Our psychiatric wards, juvenile halls, foster homes and prisons are full of examples of such parental failure. If we choose to attribute irresponsible behavior to illness, we fail to accept our primary job as parents. If we believe that misbehavior is the result of some psychiatric abnormality in our children, we will tend to seek treatment for them rather than to correct their behavior ourselves.
Treatment is the job of therapists.
If we believe in the illness, we will hand over our work to them. Quite to the contrary, you'll feel sorry for your poor sick child and make excuses for his behavior. You'll feel guilty if you get angry at his irresponsibility. You'll sit around waiting for the therapist to do something, feeling increasingly helpless as time goes on. Your kid will continue to win the great conflict.