I think this is where the argument for short term whole-residence rentals breaks down.
In the beginning, Airbnb was for homeowners and renters to provide a spare bedroom to travelers. In that case, they're facilitating a private transaction between two individuals to exchange money for a place to crash. By the residents staying at the home for the duration of the guest's stay, it's hard to call that a sublet, and there's a very strong argument to be made that it's just a communications platform to link either side of a marketplace.
But the case of whole-home rentals gets murkier. I don't see how letting someone stay in your home while you're living somewhere else is anything but a sublet. And if it is a sublet, why should it not have to conform to the established rules for sublets?
I find it disappointing that the Airbnb team hasn't done much in the way of explaining this point. When they do address the legality of Airbnb, they almost always refer to the first case. It's understandable, as it's a much more easily defensible position. I'd be interested to hear someone from Airbnb directly address the possibility of their service being used to turn residential spaces into commercial spaces (in the form of hotels).