Comment by SoftTalker

Crews "time out" due to regulations governing duty hours, not airline policy. Many things can delay or disrupt travel, including weather, mechanical problems (which to a degree may be on the airline but random failures happen too), closures or bad weather at your destination, or at other airports that are creating a backlog of diversions at your destination. It's unreasonable to expect that even the best-intentioned airline can avoid all of that all of the time.

Travel insurance is can be purchased for situations where a delay or canceled flight would create unusual costs for the traveler.