When I flick on the light switch, I am consuming electricty. It doesn't matter to me at the moment of consumption where it is coming from as long as:
- It is there when I want it
- It comes on instantly
- It delivers enough of it to power the bulb
- It doesn't cause a breaker to trip
- It doesn't cause the bulb to explode
I could satisfy that need through several mechanisms:
- I could have it delivered to my house from a central distribution facility
- I could make it myself
- I could steal it from a neighbour
Similarly in the software defined infrastructure world, the application that is running doesn't really care how the infrastructure it is running on was provisioned. The "as a service" part of IaaS is about the procurement of the environment on which the application runs.
The procurement model can, of course affect the physical environment of the equipment. Just as delivering electricity to my house requires cable, effects on the landscape, metering, centralized capacity management we have to have those kinds of capabilities in our IaaS procurement worlds. No argument there, but at the end of the day it's about how the capability is delivered and paid for, not in how it operates that really matters.