One other compounding problem is that Delta's headquarters and main traffic patterns are on the east coast. Crowdstrike affected all the airlines at roughly the same time. This gave them roughly one to two fewer hours to respond before they hit their morning peak flights.

As someone else pointed out, they probably weren't ready by the time they needed their systems for the morning rush so they went to their business continuity strategy (manual). This has a throughput and recovery time penalty and obviously it compounds the longer they are in that mode.

I think what we're finding with the Southwest meltdown and now the Delta meltdown is that the big airlines just don't have the manpower or scheduling slack to accommodate going into business continuity. I do think this should be investigated. Hopefully financial penalties incentivize action but time will tell.