The big problem with Frontier (and Spirit) is that they won't put you on another airline and have thin schedules (e.g. only 2x or 3x weekly for some routes). So that means that even a rebooking could mean delays of more than a day. Frontier's official policy (as per USDOT website) is not to pay for hotels, even if they can't play the weather or ATC cards.

*Maybe* if you're in a city with thin service and stuck, you could get a connecting flight, though that could entail an overnight layover in DEN, MCO, LAS, etc.

And on top of that, is it's a busy period the options to rebook could be totally full and you'd be told you have to go standby. Can happen especially in peak summer months and over Christmas.

BTW, one of the more infuriating delay-causing things that I'm seeing more and more of with Frontier is having to wait on the ramp, sometimes 30-60 minutes, because of an occupied gate. A recent flight I was on that was 45 or so minutes late getting out of the airport had an additional 40 minute delay because the gate at the destination airport was occupied. They had scheduled things so tightly that the occupying aircraft was due in for that time slot and the late-arriving one had to wait.

Imagine having a connection and watching the last hope of making it slip by because they can't pull into the gate.