IMO Apple's planned obsolescence is based on ridiculously low RAM. Modern phones are running same workloads as modern computers. Browser engine is the same, kernel is the same. Phone CPU is as powerful as laptop CPU with similar power budget. Developers use same or similar frameworks to write apps. Imagine buying premium laptop with 2 GB of RAM. That's iPhone 8 while high-end Androids were shipping with 8+ GB of RAM at that time.
RAM requirements of OS and apps will increase every year, so it'll be obvious to stop supporting old phones because of lack of RAM, even if CPU and Disk are more than capable.
RAM requirements of OS and apps will increase every year, so it'll be obvious to stop supporting old phones because of lack of RAM, even if CPU and Disk are more than capable.