The worrying part is that in order to keep using the good MacBooks from the past, you need to keep them on the OS version that they shipped with.
I have a 2012 MacBook Air that was crazy fast, weighed four grams, and even ran windows 7. Sure, the drive was small, but it was perfect.
But some time in 2015 or so I made the terrible strategic blunder of upgrading to the latest OS version. Performance immediately dropped to zero, and now when I open it up for any reason, I just spend my whole time watching it spin uselessly trying to idle along with one browser tab open. It's sad to see it so reduced.
I've had the same experience with every iPad I've ever owned. Delightful, responsive machines that get auto-updated to brick status over the course of about three years. (I have every model up to air 3, and the only one still working perfectly is the old 1st gen air that I've kept on iOS 8 and spend a minute every day carefully dismissing the auto update prompt).
I have one of the sacred 2015 MacBook Pros, which now can't edit videos using the new format exported from my wife's iPhone x. An OS upgrade would solve that. But the machine is too precious to risk it.
I don't know what the solution is.