Fair enough, I was just spitballing.
I'm taking my last shelf of M3 this week. Loved my outpatient FM, IM, and peds. I'm applying to FM in the fall, started out strongly considering primary care among 1-2 other things I ended up not enjoying on rotations.
And since you think M4 is useless anyway, that makes me basically the same level as you, right?
While the zebras are not the bread and butter of PCPs, you will have patients with zebras. On my primary care months, my attendings saw patients with all kinds uncommon conditions - tuberous sclerosis, Dandy-Walker, biliary atresia, G6PD deficiency, Marfan's, CREST syndrome, didelphys uterus...this is all stuff I saw in 2-3 months of primary care experience, so one weird thing every week or two. Patients will often initially present to their PCP with complaints related to these diseases. The PCP may not take point on managing these conditions in the long term, but they are the ones who have to recognize what it might be, start the initial workup or even diagnose the condition themselves, make the right referrals, help coordinate long-term management, and know what special screenings and health maintenance might be needed for that patient. I'm certainly not saying PCPs are solely responsible for diagnosing and managing these conditions, nor are they super common compared to the other stuff you listed, but you will have patients who have them and it will benefit you and your patient to have seen a patient with this condition before.
So again, I don't see how the potential for exposure to more zebras and more complicated patients is a bad thing for primary care providers.