I wish someone would take the time to benchmark how stark the performance difference is between Day 0, Day 365, Day 730, etc. of doing the same exact tasks on a factory reset device with whatever is the latest software version at that time.

It's not hard to roll out new features behind flags for devices which can't reasonably support them. But your experience of ridiculous lag trying to open basic apps which have no particularly high resource requirement has been my experience exactly.

There's more going on than simply, "we added new features!" Devices which on Day 0 are blazingly fast and incredibly responsive because literally unusable in a few years doing exactly the same tasks.