One extreme defensive move for an enterprise would be to implement full redundancy for anything not hosted on-premises. Redundancy for data protection is relatively straightforward, but having multiple email, supply chain, or e-commerce services is very expensive and disruptive. What are the odds that it would even be needed? Whatever those odds were, they just became much higher.

This is simply dumb. The odds are greater than zero. you must have a disaster plan. It sucks that MS did this but I don’t have much sympathy for anyone that decided to save money by ignoring DR.