Let's take a hypothetical situation where I create an outdoor hippie movie theater. In the beginning, the incentives for people to go to this theater would be my playlist of movies, i.e. how good my taste in movies are.
Suppose I then allow nerds to post their own playlists for showing in my domain. The effectiveness of my movie theater would be degraded by poor choices made by said nerds.
If I create and own the medium in which art is expressed, then I should be able to control who sees what. Consider the museum that allows people to bring in their own paintings for display.
I believe that in pursuing a business model in opposition of net neutrality, businesses are better off in controlling their costs.
By restricting access to the Internet, the marketplace will find better methods of content distribution. Perhaps radioactive brain waves, who knows?