I hate that in a sense you're right. The problem is that in a practical sense it's become so much more than that, too. So due to the law of unintended consequences, the psychiatrists that wrote the manual have built their own prison (if you'll excuse the mixed metaphors).

To me, it seems that psychiatrists/psychologists need one manual for GPs, another manual amongst themselves, and a third written to placate US insurance companies. Right now they all use the DSM because it's the only thing.