I would say that this could be argued for many disorders in the DSM-- however, we don't typically diagnose for the purpose of figuring the underlying causes.

ODD is a behavioral disorder, not a personality disorder-- however, I think it can be said that like personality disorders, it has to do with a child's way of coping when proper coping mechanisms are not in place.

I think it is okay to say that it has to be treated because no child should have to behave like that in order to survive-- the person benefits from the treatment because he/she does not have alternative ways of behaving. The parent also benefits from the treatment because it often involves parent training models and learning healthier ways of managing/extinguishing behaviors.

A "disorder" comes about if a disturbance is outside what would be considered "normal." In this case, the behaviors are seriously interfering with the child's ability to function in home, school, or social situations. For that reason, it becomes a disorder. Similarly, borderline personality d/o is a disorder, because, regarless of how the person go to that point, it is a serious disturbance of functioning-- the person is in need of treatment.

So while I don't think it is wrong to call something a disorder, I agree that we should always be looking out for "why" something occurs, and how it can be treated to become more manageable.