I mean, I'm sure there are a few, but if I'm a landlord, why would I give up having a stable tenant paying market rate rent for 12 months at a time for essentially managing a hotel room?
Sure, the 'rent per day' is going to be a lot better with the hotel room model, but it seems like an entirely different business to manage say 30-100 property rentals per year rather than 1.
People have always subletted their apartments when they are out of town -- I'm guessing a lot of the Airbnb rentals are just those traditional sublets showing up in an easy to quantify form.
I'm open minded to the possibility I'm wrong -- I don't have the data on the history of the properties showing up on Airbnb -- but it seems like the profile for the landlord/apartment that ends up on Airbnb is a bit different from the ones that show up on StreetEasy with 12 month leases.