Although I've only been in officiating for a few years (and only do basketball) it seems to me that the "opportunity to show yourself" is much harder in football than in basketball. There are fewer camps, there are fewer college teams, etc.
Locally, I've heard that unless you have 20 years of experience you will not touch a state playoff game, and most of the guys in the championship have 30 years. (this is coming from a friend who has had success in football and carries no bitterness toward the situation) I don't think it's a good ole' boys thing, since the assigner is well liked. He even runs the wings and works junior high games.. who does that?
All that to say I'm grateful for the chance to get out there and prove myself in basketball, so I don't think I'd cross the line, but if I was a football official it would be very tempting not to if the NFL was taking applications.