Rural general practice certainly differs from that in urban areas, perhaps more so in 1948. Nowadays, there are few GPs left over from the days before the specialty of family practice emerged, but in an urban setting, you would never see a family practitioner perform surgery, such as this Life magazine article showed. In rural areas, family practitioners will do obstetrics and may also do Cesarean sections, as well as common surgeries such as appendectomies, but quite often, air ambulance is used to get patients to a specialist when warranted.
I think the author of this current article is unclear on the driving factors behind specialization in medicine. It is not greed, or at least not commonly, but a combination of the increasing complexity of medicine and expansion of the amount of learning required, the advanced care that can be accomplished with a specialized knowledge base, and interest in the field on the part of the doctor. We benefit from specialization — would anyone with a serious illness refuse to go to the ICU or see a cardiologist, for example, if their life was on the line? Even in less dire circumstances, such as musculoskeletal (MSK) conditions, doctors outside of the MSK specialties (e.g., orthopedics, sports medicine, rheumatology, physiatry) cannot be aware of the fast pace of progress of the type of care that can be delivered. So before we decry specialization, we need to step back and take a broader view.