This is a very cynical and hostile view of Apple fighting for the privacy of its customers. If Apple were prioritizing defending their walled garden over privacy, they wouldn't have put strong encryption on iMessage and other services.

Apple's walled garden in itself is a privacy/ protection mechanism for their customers. iPhones and iPads were made to have the average in mind, so loading bespoke software removes the risk of spyware and adware that plagues devices without these protections.