Apple markets its own products, not whatever is in their store (with some early exceptions). Apple benefits from third party developers, third party developers

Apple markets its own products, not whatever is in their store (with some early exceptions). Apple benefits from third party developers, third party developers benefit from Apple. Third party developers don't get a slice of iPhone sales revenue. You wouldn't support Kitchenaid only allowing curated vegetables and charging their vendors 30% (or even 3%).