Even forcing competing app stores has problems. It's Apple that will be forced to provide support for those app stores. If someone installs malicious software f

Even forcing competing app stores has problems. It's Apple that will be forced to provide support for those app stores. If someone installs malicious software from one and it bricks their phone they're going to bring it to an Apple store. Even if they have a policy of "competing app stores mean no support" there's still going to be the time wasted determining if another app store was used and the good will lost when customers find they no longer receive support for their broken phone.