Certainly it applies in the business world. If Company A does wrong by a customer, that customer switches to a competitor, Company B. That is lost money for Company A. So to an extent, the adage "Customer is always right" should be heeded by any business wanting to keep its clients happy and therefore stay in business.
I say "to an extent" because it's not always possible. For instance, the adage doesn't apply in this case, because the user who used it against Ian was simply mad because the feature he wanted in a game isn't in the game. Developers can't include every feature that everyone wants, especially when some features aren't possible without the developer breaking contract with it's partners (in this case, the NFL).