I wonder if the Airbnb team has ever thought about their profit and its relationship to the externalities you describe. As a customer, I've felt like I pay for something and then bear lots of risk if it goes wrong, but the discount often isn't sufficient to cover that risk.

At the end of the day, it may still be a good thing for the temporary housing marketplace if people who want certainty (in general or just for the trip) stay in a hotel, and people who are willing to trade certainty for some savings stay in Airbnbs. This would lower demand for hotels, and therefore cost. But this is only an efficient outcome if Airbnb guests understand how the company will leave them high and dry if something goes wrong.