While it may be impossible to meet staffing demands for such events, they reduce staffing needs by an order of magnitude with effective online rebooking systems. Instead, carriers are slow to automatically rebook, online rescheduling is glitchy, and many website users get messages telling them they cannot rebook online and must call instead. Whether this is managerial incompetence, cost-saving measures, legacy software systems, or something else, I don't know.
*There's something darker going on as well.* Some of the inconvenience that US travelers are suffering is built into the system on purpose. Sales platforms are convenient by design because companies don't want to lose sales. Customer service platforms are inconvenient by design because the sale has already been made. Inconvenience makes people go away– and making people go away saves money.