In Dr Weiss and his co-author's mind, the foreskin cannot have functions. It must be presented as completely useless, against all empiric evidence, to make its ablation more palatable. However, the deception goes beyond that. Circumcision is not a medical procedure, although it has disguised itself as such in 20th Century America. It is a form of genital mutilation required by some religions as a ritual of passage or entrance into the community of believers.
Similar rituals affect men and women in many societies around the world, past and present.
Female circumcision in this basic sense is no different from male circumcision. Among the religions requiring the circumcision of the new born male, the most notorious is Judaism. Coincidentally, Dr Weiss is Jewish, and a practicing Jew at that. Many people in the US, affected themelves by circumcision, feel a need to deny the mutilatory nature of the procedure, and vehemently reject any criticism of circumcision. This book obviously is for them.