The topic is opening up the app store, allowing developers to implement their own payments, and someone asked: "where is the evidence that letting developers choose how to process payments leads to rampant fraud?"

Well, Android is open to sideloading and less "walled" and ends up with 50 times more malware than IOS. That's what "that article" is about.

If someone connects the dots, they'll see that (a) opening up iOS similarly will lead to similar levels of malware, (b) letting developers have their own payment systems in such an environment would just lead to tons of that malware getting people's credit card details, charging for BS, and so on.