This raises an interesting difference between hotel and airline programs. With most hotel programs, you can book a guaranteed room, be a no show, pay for the room, and get credit for the stay.

So the question then is why you can't buy a nonrefundable airline ticket, don't fly, and get credit for the flight.

It used to be a problem because you could exchange a NR ticket for a new one with a $100 svc fee. However, now the airlines have software that requires you to cancel the reservation before flight date in order to have the residual funds available for the exchange. If you don't cancel the reservation, you lose your money. So now, theoretically at least, it could be the same as a hotel no-show.