[geofft]

Yes, it is, and that's precisely why the removal of homosexuality from the DSM (in 1974) was not a sign of the DSM's authors giving into cultural pressures - it was a combination of the authors avoiding the cultural pressures that had caused the previous edition to list it, plus a realization (after scientific study) that the problem wasn't with the person, it was with their society.

The nature of the scientific method is that we learn new things over time, and the nature of society is that we are all subject to various kinds of cultural pressures, most of which we don't even recognize. The meta-level goal of the DSM - describing those disorders which prevent someone from thriving and are properly treated by psychiatrists - seems sound, even if each edition always needs to be succeeded by a new one.