This is a good point. If an app does me wrong with a non Apple payment processor I can do a chargeback as a last resort. That's not really an option for Apple payment processing because I think it can get your whole Apple account banned.
That is also true. There is a very significant disincentive to charge back against sellers protected by Apple, Microsoft, Google, Amazon, PayPal, Stripe, and other similar payment gateways. The consumer protections are, therefore, eroded.