Like your cohort Mitch, it's obvious you have no idea the scope of airport operations and what they must deal with in a storm.  For a busy airport like SEATAC, every takeoff and landing is carefully scheduled every 1-2 mins throughout the day, and any activity that will cause deviation from the packed schedule (clearing the runway, de-icing the planes) throws the schedule into chaos, as even a short 2-3 minute task will push the entire schedule back, keeping some planes from taking off and others circling in the air, unable to land.  Furthermore, Air Traffic Control will prevent planes taking off from other airports bound for Seattle unless they will have a known, guaranteed space in the schedule to land.  All of this compounds on each other, forcing delays and cancellations.  An airport like Anchorage, while busy, is nowhere near as large and busy as SEATAC, and much better able to adjust their schedule to allow for unexpected tasks associated with storms, and not force rolling delays