Smaller developers aren't being ripped off, not anymore. There's a philosophical argument that Apple shouldn't control your device, but that really has nothing to do with the 30% they charge larger companies.
I'm making the opposite of a philosophical argument, I'm making a practical one. Apple is not going to take away the App Store, or make it too difficult for developers to upload apps, since that would be a real threat to their iPhone business.
Developers need Apple, but Apple needs developers too. Currently their market domination makes it an extremely hard collective action problem for developers. Not being on the App Store means losing out on the majority of your revenue, which makes it tough for enough developers to band together against Apple.
Can we stop pretending the app store fee is just for payment processing?
This tells us nothing about the charge being only for payment processing.
Right now you as a developer pay $X for access to their eco system, and on top of that you pay 15/30% of whatever payments they process for you.
You can say "well actually, that 30% isn't all for the payment processing" but I don't why it matters what Apple's intention behind the payment is.
Businesses rarely map charges directly into what is being paid for, because that doesn’t work in practice. Charges are made at a convenient point and then used to pay for the service as a whole. This is common practice across all kinds of business.
This matters because people are claiming they it is just for payment processing and then arguing that 30% is too much, which is clearly a dishonest position.