Why is the rule ridiculous? It did exactly what it was intended to do - reduce or eliminate endless tarmac delays. One way it achieves this goal is that it forces airlines to look forward and make an intelligent assessment about whether this flight has a real chance of going out within 3 hours. If not, it gets cancelled right up front, leaving passengers the option to make other arrangements, or even to go back home if just starting a trip. Regardless, you now have options, something you didn't have in the past when you were on the tarmac for 7 hours.

I say Good Job.