TL;DR sometimes it's not Apple, it's the app devs that deprecate them.
Since linux runs on it, I can run the latest versions of great pieces of software like ed, slack in a web browser, etc.
It is 100% apple's fault that they do not open up the bootloader for devices they'll no longer offer updates for and allow the community to build a custom darwin or linux fork. Even though we paid for the hardware, we are not allowed to use it any longer than apple says.
Are the app devs deprecating just because their support matrix is too big, or because current SDKs will no longer build apps compatible with those devices?
I think the later case is less common on the Android side of the fence, but Apple is not great about keeping old versions of the dev tools functional, and you end up needing to keep elderly Macs around to target older versions of the OS.