A couple of years ago I took a trip on America West near the end of the year to meet my Continental Elite requirements. It was a day trip TUS-PHX-SAN and return. The PHX-SAN flight was overbooked, and they were offering $400 to wait 3 hours for a later flight.
I considered the offer, and since the 3 hours would take up a good part of the time I had planned for sightseeing, I asked if they could just send me back to TUS, but credit me for milage for the entire trip.
The answer was no, and I stayed on the plane.
Stupid, yes, but rules are rules!