That's not even going into the monetization pieces. As we are implementing tipping and multi-merchant subscriptions in Post+, we still have to use In-App-Purchases with it's severely lacking API.
The hoops we have to go through to get money from our App Store account to merchants are insane. We are using Stripe Connect infrastructure and Payouts API to do that, and that would be totally fine, as well as taking the fee hit.
The most insane thing is that the subscriber can be in a number of countries, where Apple fees differ (as they contain tax). But the webhook does not contain this information, so we had to reverse engineer the whole Apple pricing matrix and the fee calculation for each subscriber to know what portion to forward onto the Stripe account, and so on and so on.
It's been a ride.