It's only a liability if the holder of that debt has a reasonable chance of collecting on it.

lensman's view is more on target than any comparison to an open monetary system. The airlines have created an artificial currency that may not be easily transferred, bartered or sold, and control all redemptions into services. Unlike US Dollars, you can't take it and move it into alternative outlets.

As I have mentioned before in these types of discussions, a redemption that is refused ("yes, the flight will be departing with empty seats available, but they are not for award travel") by the airline really isn't a liability.

If the government allowed me to print up and hand out $1,000,000 worth of Tino currency annually, while only having to honor $500,000 of redemptions a year, am I making money? The accountant would say no - there is a liability building up. What does logic tell you?

The value of a mile has already plunged and will continue to do so. Every joker that quotes their "2 cent mantra" gets a response from me offering as many as they want at that price. No takers so far!

I laugh at those who must value their precious hours on earth at less than minimum wage to sit on a plane and accumulate even more of this funny money.