To be honest I quite agree with ATC Watcher. If the airlines did not have pay any of the expenses they would not have any incentive to get you to your destination whenever the circumstances improve.
So imagine the airport closes for two days, and there is one airline that flies there once per day with an 80% occupancy. Once the airport reopens, It would take more than a week to clear up the backlog unless schedule extra flights. You may arrive to your destination after your original return date, and to make things worst, the airline may refuse to refund the return leg because “the return flight operated as scheduled, and you did not arrive to the airport in time” (it happened to me as well).