Metamorphosis isn’t supposed to look this easy. Microsoft has been shifting its decades-old products to the cloud without having to make a single insurance claim for business interruption. Indeed, revenue rose 13% in the quarter ended June 2017, while earnings doubled.

As customers increasingly choose to carry on their computing and data storage in the cloud—that is, in shared data centers operated by the likes of Amazon.com (ticker: AMZN), Alphabet (GOOGL), and Microsoft (MSFT)—instead of on the customers’ own premises,…