Well, here's a counterpoint. A bunch of people in my building use AirBnB to rent out units. These transient tenants are often noisy, dirty, and in one recent case, outright frightening, threatening long-term tenants (security had to kick him out of the building). Hotels are zoned differently than residential units for good reasons, it's not just big business squeezing out the small fries.
That's not to say I don't have full respect for you as a company. Just want you to be aware there is a counterpoint, and that people using your service should be following local regulations and leases. When they don't, it creates headaches for neighbors and resentment towards your company.
Since then I've realized that the positive impact goes far deeper. For example, as a host I tell every guest about my favorite local establishments. Not only am I exposing my guests to true San Francisco flavor, I'm also helping local businesses that don't traditionally see tourism dollars.
There isn't a day that goes by that I don't hear about how we've helped someone, both travelers and hosts.