People want Instant gratification! I have 2 friend who decided to try Primal. Both, after only 2 or 3 days, said " Oh, your diet (My diet!) is making me feel sick, it's obviously not for me".
They never even got past the "Carb flu", which I had warned them about.
The people who stick with this are in it for the health benefits and are in for the long haul. Yes, we may tweak things here and there from time to time, but we're "core" Primal.