Very few non-classic and/or popular cars receive massive aftermarket support for all parts - often the aftermarket supports parts that are in common with a lot of vehicles or are vehicle-agnostic (such as belts, etc), and in some cases you're plain SOL (try replacing an airbag on a 1993 Dodge Caravan, for example - all you can find are OEM used ones pulled from junkers).
I think your comparison would be more apt if, say, Ford disabled all vehicles that were 10 years + 1 day old. While Apple isn't disabling your OS, they leave you exposed without security patches, etc... - making it approximately the same.
How long do we have to wait for the early Teslas to be considered "classics", because they're doing worse than this already...
"Self driving? No, that was only licensed to the original purchaser, you need to pay us $8000 now because we just remote disabled it when we worked out you bought this Roadster second hand. Hope that helps, have a nice day - Elon"
I feel the same way about computers - like, who gives a damn what apple thinks. I have a laptop that is still going because people keep making it compatible. That's a good thing, not a bad thing.