- iCloud free tier is 5gb -- not enough for even a casual phone user with 1 minute 4k 60fps video (option on iPhones for 2-3 years now) takes 400mb.
- The alternative to "paid" apps are ad-supported apps. You're paying either with your bank account or your data and attention. I don't think we should call this optional and otherwise encourage ad-based ecosystem. (And, side note, I argue Apple should also tax ad revenue to prevent the current artificial advantage ad revenue has over IAP.)
The rent seeking point from Stratechery is taken directly from Apple's own earnings calls where they are now measuring their success based on revenue from this rent-seeking instead of on devices sold.
Whatever is measured will drive the company focus. To sell more devices they have to innovate and increase excellence. To increase rents they have to wring more and more $$ from existing users (with a secondary focus on increasing the hassle of switching). Apple themselves explain that they have shifted their focus from the former to the latter.