In one of Moz's technical blog posts they mentioned that running the couple of instances needed to process the raw search data equated to $700k. That's fucking insane. They could run a couple of dedicated servers for a fraction of the cost and get a hell of a lot more performance.
It was around this time they mentioned that they were building their own private cloud so at least they saw the writing on the wall - AWS wasn't suited to their use case.
Yep, and in my experience getting developers to wrap their head around decoupling systems and make sure the system is always decoupled is difficult.