I believe that businesses are free to do whatever they want within the law. However, once a company reaches a certain level of power over an entire market, the antitrust laws forbid those companies from distorting competition. I believe that Valve is taking away gamers' freedom to choose how much extra they are willing to pay to use their platform. I believe they are taking away competing stores' freedom to compete by taking advantage of their lower commission rates. I believe they are taking away developers' freedom to use different pricing models.