Except get security updates that are only ever packaged in newer OS releases, for one thing.
I get where you're coming from, but this is the fundamental problem with network-connected devices. I'm an Apple fan, of sorts, and my whole family is part of the Apple ecosystem, but the company has a nasty habit of strategic obsolescence and doubly so around transitions.
I'm giving this an upvote, because I have a MacBook 1,1 from 2006 that runs Windows 10. That's 14 years of support & security updates from Microsoft, and they didn't even make the device.
I get where you're coming from, but this is the fundamental problem with network-connected devices. I'm an Apple fan, of sorts, and my whole family is part of the Apple ecosystem, but the company has a nasty habit of strategic obsolescence and doubly so around transitions.