You are right on target. With the explosion of medical knowledge, there's absolutely no way that primary care physicians can know it all and do everything like the general docs of 50 years ago, much like general surgeons don't operate on nearly every organ system in the body like they did 50 years ago; maybe unless primary care residency programs want to lengthen the duration of residency. I'm in a surgical subspecialty in which there are talks of extending the residency to 6 years (rather than 5) because the amount of information keeps growing so rapidly, and with duty hours restrictions there's less time to see and do everything.
From my experience in multiple academic and private clinic settings, this is the direction that healthcare is going: the PCP's will generally try treating diseases like sinusitis, sleep apnea, otitis media, etc. with the first line treatments, and if they aren't seeing results then they'll refer them to us. Reading the NP notes, they generally have a laundry list of problems in the note because they spent an hour listening to the patient's every complaint, then each complaint gets referred out to a specialist instead of actually trying to be treated. Got sinus problems? ENT consult. Aching back? Neurosurgery consult. Headaches? Neurology consult. Trouble urinating? Off to urology. Etc. etc. As a result of this, patients are now going to primary care docs and pretty much demanding to be referred to subspecialists for problems that don't need subspecialty care, because that's what they expect. The end results is that a lot of specialty clinics (including mine) are being overrun with patients who absolutely do not need to be seen by a specialist and can easily be managed by a well-trained primary care doc. Not only is that driving up the cost of healthcare, but it is also taking time away from patients in clinic who have legitimate surgically manageable diseases. This is what scares me the most about the rise of mid-level providers seeing patients unsupervised, because while our clinics are being flooded with unnecessary patients, I cannot tell you the number of delayed cancer diagnoses I have made (often in the ED) that have been completely missed by NP's, who are treating all sore throats and lymphadenopathy with antibiotics. Is that being published? No, because I don't have the time to try to bash NP care in the public forum; I have better things to do in my time.