I have just been in a forum where a very simple question was asked:
Does anyone use Amazon web hosting?
Very quickly it became : Can I get a VPS from them?
There is a such a mind shift from hosting a WordPress website to running an application such as Netflix. The whole discipline, IT infrastructure, processes, business objectives and SLAs are staggeringly different.
This article about Netflix, who are on the Amazon infrastructure, shows how they test their systems and should give an insight into the fact that we are not talking about different worlds, but actually, we exist in parallel universes when we talk about simple hosting versus cloud.