It is very hard to decouple yourself from the tooling and the platform specific features. The PaaS offering literally requires half of the additional services ad the basic deployment is simple and the IaaS offering is expensive and you need the latter to decouple effectively.
Either way you also hang yourself with a vendor tied product and the ball and chain of licensing. The latter of which escalates pretty quick when your business grows.
Our 8 man startup in 2005 now spends £200k a year on licensing because we're that tied to the damn platform.