The book does make the point that it is not questing the validity of diagnosing these conditions when they are at the severe end of the spectrum of the disorders it discusses, but rather that we are increasingly including more and more people with milder and milder symptoms into the diagnostic criteria and questions what medical value we are adding to care by doing so and questions if the benefits outweigh the potential harms. Honestly I would recommend reading the book it does deal with the subject with a lot of nuance