(above) Yeah I'll buy that. There are lots of things on bikes that are unnecessary overkill, my first good bike, a Cannondale road racer, was very much along those lines.

EDIT: I would say though, if phosphating reduces paint chipping (better paint adhesion), that is noticeable. A bike frame I stripped and painted in my teens, pretty, but paint would chip very easy. Sandblasting before prime and paint would help, but is such a pain doing it out in the driveway and sweeping up the sand ten or twenty times, if you don't have a blasting cabinet.