In the case of companies like Steam the answer is: Because some products are not available elsewhere. So it's not that you want to do business with them but that not doing business with them also cuts you off from a large number of other companies. Similarily, if your water company overcharges you then you still want to be able to get water even if you need to charge back or take them to court over the dispute. In some way, Steam has taken over the role of infrastructure for Game delivery and I don't think its unreasonable to recognize that by applying different rules to them in the same way your local power and water companies get different rules from a mom&pop store.