Okay, first of all: the DSM is used primarily in North America. The majority of the world uses ICDM.

Secondly, the DSM has gone through many iterations and changes. For instance, DSM-I and -II contained psychopathy as a mental illness. It was replaced by ASPD in DSM-III. What we term today as "major depressive disorder" was also introduced in DSM-III. Did depression not exist prior to the third DSM? Did ASPD not exist? Does psychopathy not exist now that it has been replaced by ASPD?

Thirdly, there's so much bloody overlap in conditions listed in the DSM that you could present two psychiatrists with the same list of symptoms and they would diagnose two different disorders. And to my mind, this lends more credence to the first DSM's principle classifications of psychotic, neurotic, and behavioural disorders.

To summarize, the DSM is regional and therefore cannot be applied globally. It describes medical conditions and those medical conditions can be redefined at any time. And it is borderline unreliable due to diagnostic confusion and overspecification. In short, the presence or lack thereof of some cluster of symptoms in the DSM is not an indicator of the existence of a condition.