This is a badly reasoned article. If the total stock of vehicles is decreasing it creates a lot of savings (as the article admits). How are these savings captured? In cheaper Ubers. The total cost of all the cars on the road is already being paid for out of our transportation costs. As each vehicle gets shared between more people the cost to each person goes down. Obviously there will be an equilibrium between lower prices from fewer vehicles and higher convenience from having extra capacity. But, using resources more efficiently won't cause harm. Even if the total vehicle stock were to decrease as much as the article suggests the price of an uber would drop much faster than the convenience.

Now this all assumes an efficient market. If Uber were to start abusing its monopoly powers, that would be something to be legitimately concerned about...