PIP is a result of a confluence of factors. It can be the raws, it can be the oil, it can be the solvents, could be the sterility etc etc etc. Any one of those factors can cause PIP on its own at various levels for individuals due to genetics.
For me, the type of pain varies depending on the cause. I'm intolerant to solvents like EO, I get bad swelling and intense pain & inflammation.
But for a compound like primo, I get no swelling or inflammation but a bit of soreness after a day or two, a very different sensation from solvent caused PIP.
Haven't had a bad reaction to an oil having only used mct and gso.
Just my .02 from my background and firsthand experience. I think it's incorrect to assert that all PIP boils down to one variable when there are several that can cause issues.