> If I buy a house in a neighbourhood that is zoned single family residential, Am I an "inefficient incumbent" because I expect that over the mid-to-long term it will stay that way?

The incumbents I was referring to are clearly hotels and taxis. But I think it's also important to point out that I wouldn't presume to tell you who to rent to or for what duration since you own the home and it's your property. AirBnB is merely a facilitator of that transaction.

If you don't own the property, that's different story.