Zillow is only one of the companies that are buying homes and reselling them. Does it hurt the market? Actually it could go either way.
On one side it maybe takes a bunch of potential sellers off the market that would have probable not used a Realtor anyway. This means less for sale by owners out there.
On The other side we are competing with another brokerage that is like the King Kong of real estate lead generation. I am sure they will get there in home sells as well. We will just have to see.