I don't have a ton of experience with Airbnb, but from what I can tell, it serves three primary functions.
The first is to provide affordable and more personalized lodging for people visiting from out of town. The second is to make life a lot harder for people who want to find an apartment building that hasn't been converted into a sketchy hotel.
The third, however, is far and away the most enjoyable aspect of the Airbnb experience: You get to judge total strangers for the things they have in their places.
As of right now, you have to book an entire night to snoop through another person's possessions, but Above Average is trying to change that with Airbnb Express.
Why pay the full price when you can pay for a couple of hours to send your friends as many pictures of someone's disturbingly large katana collection?
You're right -- it doesn't make any sense.