I listened to DCA air traffic control around 3-4pm on the 25th. DCA closed for about an hour because of thunderstorms, meaning the airspace was empty and about 15 planes were stuck idling on the tarmac. Saw one AA flight inbound from Florida doing loop-de-loops near Richmond for an hour. OP drew an unlucky slot in the sequence, but when air traffic control says, "you're not taking off" or "stay out of our airspace" you're not going anywhere.
Obviously this is a different airport but it's an example of a situation where it's easy to blame AA, even though the delay had zero to do with any choice made by AA. As others have mentioned, the East coast was a mess yesterday. That's one slice of what it looked like.