The same reason Craigslist didn't like Padmapper scraping all their listings: The listings bootstrap a competitor who will later try to replace them. Example:
1. Get sellers used to visiting www.beyondpricing.com instead of www.airbnb.com - you don't have any problems attracting sellers, because you can get their listing in front of as many people as airbnb.
2. Add some sort of multi-site listing search or something, to get buyers also visiting you directly instead of going via airbnb. Advertise your site on your sellers' airbnb listings.
3. Once buyers and sellers are used to using your site instead of airbnb, launch your own listings service and cut airbnb out all together. (Or better yet, launch your own listings and only invite the profitable low maintenance buyers and sellers with established histories, leaving the dregs to airbnb)
This allows you to sidestep the problem of "sellers don't want to use us as there are no buyers, buyers don't want to use us because there are no sellers".
1. Get sellers used to visiting www.beyondpricing.com instead of www.airbnb.com - you don't have any problems attracting sellers, because you can get their listing in front of as many people as airbnb.
2. Add some sort of multi-site listing search or something, to get buyers also visiting you directly instead of going via airbnb. Advertise your site on your sellers' airbnb listings.
3. Once buyers and sellers are used to using your site instead of airbnb, launch your own listings service and cut airbnb out all together. (Or better yet, launch your own listings and only invite the profitable low maintenance buyers and sellers with established histories, leaving the dregs to airbnb)
This allows you to sidestep the problem of "sellers don't want to use us as there are no buyers, buyers don't want to use us because there are no sellers".