To be fair (and I'm sure you're already aware of this), DL, AA or UA would likely have been able to provide other routing options.

I missed a connection in JFK on B6 traveling from PWM to RDU where both the PWM->JFK and JFK->RDU flights were technically on-time*, and it resulted in me spending 8 hours in the Airside Lounge awaiting the next JFK->RDU flight. There simply weren't any other options that would have gotten me to RDU in a timely fashion.

I'm reasonably certain that wouldn't have been the case with the other 3 airlines.


* I believe that the source of the travel disruption is that the GA closed the JFK->RDU flight early.