Yeah, technically. But just everyone _normal_ just pays using Stripe often without even knowing about it. On the _walled garden_ all is so clear that my 70 years aunt is able to do it. And there is no exceptions to the rule: every subscription made through the App Store is there and it's cancellable...
30% is a robbery, and the confusion on the customer "ownership" is true, but it's not useful for the discussion to negate the advantage the _garden_ offers to the basic consumer