In three months, the App Store sent me barely a trickle of customers. Had I marketed the app myself, the traffic would have flowed the other way. I would've been sending my customers to Apple and paying a tax for the privilege.

This is a key insight: In marketing your App Store app, you work for Apple, for free.

The $99 yearly fee stays the same though, if you want them to notarize your app. But in self distributing you get to keep your customer relationships.