Not defending apple, I value having the choice personally. From Apple's perceptive allowing one vendor and not another is going to difficult, next vendor may n

Not defending apple, I value having the choice personally. From Apple's perceptive allowing one vendor and not another is going to difficult, next vendor may not be as trustworthy as 37Signals, it is considerably easier to say no other system than theirs. They have never traditionally encouraged ecosystems unless they have been forced to. I am not saying it is right, but it is consistent with their product philosophy. Same reason they absorb features from apps into the OS itself, it sucks for the developer, but it benefits the user. For example having the flash light as OS feature than an app is considerably safer, better experience.