How do you think the mood was after pax were made to show up three hours early for no reason, told they would likely be delayed for 24+ hours, and then have it hammered into their heads that it is all going to be on their dime? I did my best to calm a couple of irate pax seated in the rows around me, telling them that it would likely be fine because delays were probably cascading everywhere. In the end, they held a few international connections and rebooked everyone with a minimum of inconvenience.

I think YYZ/SD is right on the money here. This is exclusively a communications problem - an area where AC excels at outshooting itself in the foot at every chance it gets. The rules seems to be "when in doubt, piss the customer off. Even when it is pretty clear that there will be an agreeable resolution in the end."