I feel like there's a middle step missing from this article (or I just missed it reading quickly) - did they build their own data center? Where are these new non-AWS servers physically located?
Renting a dedicated server is very similar to renting a VM. It has a much higher provisioning time, usually hours to 1-2 days. And it takes some upfront cost or a time commitment. But it also has a lot more raw power. So if you don't require the flexibility VMs and the cloud provide they can be a very effective alternative.