The author of the article explains his point clearly, and in a way it makes sense when looked at it from that perspective.

I'll offer another, more pessimistic perspective. He assumes that the users paying more will get extra service, while service level for the rest will stay the same. But, it's almost never the case. In practice, the level of service for regular price will just go down, and service providers will start to charge even for something that was free, or available at lower cost before this service differentiation started.