On the scale of "no one bothered to put error handling or validation in" to "a subtle problem exists for this given input"; you and I lack the information to make a judgement.
> you and I lack the information to make a judgement.
Think about this a little harder: what do you know about the number of customers affected? We do actually have enough information to make a judgement - bricking millions of critical systems, a very high percentage of their total Windows customer population, tells us that they don’t have progressive rollouts, don’t fail into a safe mode, and that if they do have tests those tests are catastrophically unlike anything their customers run – all they had to do was launch an EC2 instance and see if it kept running.
I mean, the whole world was impacted. All they had to do was test this change in a lab with several pcs. Clearly this wasn't a edge case nor a subtle problem. This was clearly a lack of testing.
Leave the spin to the PR people. Their customers pay a great deal of money for 24x7 service, and this wasn’t even a code change but a definition update – a process which should be as well defined and tested as McDonald’s making a hamburger. You wouldn’t excuse getting E. coli from your lunch with “the cook just wanted to go home for the weekend”, and this is a much more expensive service.
Think about this a little harder: what do you know about the number of customers affected? We do actually have enough information to make a judgement - bricking millions of critical systems, a very high percentage of their total Windows customer population, tells us that they don’t have progressive rollouts, don’t fail into a safe mode, and that if they do have tests those tests are catastrophically unlike anything their customers run – all they had to do was launch an EC2 instance and see if it kept running.