In the 20 years since I've graduated college, the longest I've had the same PCP is 3 years, about half of the remainder I had for 2 years, and the rest I only saw once before they left and I had to change again. Even if they do stay, they have to see so many patients (~1000 per PCP is what I've heard) that they won't remember anything about me, and will be no better at treating me than a doctor pulled at random.
For people with chronic conditions a PCP makes sense, for the rest of us it is just another pointless loop you have to jump through.