Not if every app decides to implement their own in app subscription in order to make it harder for me to cancel or dispute. And then move their app to not the App Store. Apple provides a common playground for every app. You need to provide these things to your customers or you can play with them. I like it because it forces developers to adhere to some standards. Like for example not tracking me and not building only the subscription start part but have the cancellation behind an email I need to send.