[iforgotpassword]

It's not that much of an edge case. Sure, their load is super steady, but most other workloads are predictable enough, or rather it is still cheaper to over provision to your typical peak load and then some than doing the same entirely in the cloud. You might still get slashdotted if you have some overnight success, and whether this is acceptable in your business model then depends. You might've taken the hybrid approach where you can spin up additional resources in some cloud.