The arguments on Android are sometimes even simpler to make (which I appreciate might not be intuitive at all), as there is a space where there SHOULD be competition and clearly CAN BE competition and yet there are arguments being made that Google is going out of their way to stifle this competition regardless, by such techniques as limiting the functionality of third-party markets (a big one was preventing them from supporting automatic upgrades), or their included anti-virus software flagging alternative markets (which reminds me that I haven't caught up on the Epic lawsuit against Google recently, and really really should).