> Email is much easier and more controllable than notifications.
True, but not for the user. I would much rather accept notifications than type in my email address. I avoid the risk of getting spammed, don't need to decide what email to use, don't need to decide if I trust the developer. And with app notifications, the ability to unsubscribe is much more consistent and reliable.
People have to opt-in to in-app notifications. If they press no intentionally or accidentally, recovery is far, far more difficult. Email is much easier and more controllable than notifications.