One thing I didn't make clear, that may explain why somebody just wouldn't build their own storage/delivery: when certain services become a commodity, and long-term commitments become an exception rather than the norm - it's easier to shift the pricing pressure and uncertainty for the commodity side to your providers. You specifically don't want to "build your own" in a market like that, but instead focus on specialized, high-margin services. One exception: when you can predict/control the demand (e.g. you are a Netflix), then you build your own, and still leverage providers for capacity on tap.