It's due to rarely occurring problems such as APIs down/unresponsive, insufficient/incorrect instances available, and a third major class of problem that's fru

It's due to rarely occurring problems such as APIs down/unresponsive, insufficient/incorrect instances available, and a third major class of problem that's frustrating my memory at the moment. In addition to not scaling up and down (automatically or manually), many of these apps are architected to require as little from AWS as is possible to reduce their exposure. For example, they'll refrain from using ELB because ELB depends on EBS. These decisions were made by companies that started off believing fully in the promise of elasticity, and gradually shifted to less elastic architectures as they experienced issues. That said, it's worth noting that these are firms with very high costs of downtime, so the magnitude of failures was very high.