I'm sure this concept of part time refs is passed on from high school, to college, and then the pros, but it makes no sense in a league that is rolling in the dough, that they don't go to full-time refs. I wonder when the last time this question was posed to an NFL commissioner, and what the response was.
Bottom line...If the owners wanted full-time refs(more money), it would happen. I'll save the next poster the trouble...Ralph is cheap!