I think Valve is a good example of how to do it. Sure they also take a sizeable chunk out of sales, but they seem to compete on the same terms with their games with everyone else on Steam.

Going so far as to clearly make an unfair advantage doesn't make sense if your platform is already printing more money than you could reasonably spend. As is the case with Apple, and with Valve. Music sales are probably a drop in the ocean compared to what they make on hardware and the appstore overall. They just got greedy and started acting like assholes when it came to their competition.