It actively goes against their profit interests. If they deprecate the older devices and leave them as black boxes, that's another way to push consumers to buying the new stuff.

Something like this would have to be done with regulation.

Shares some similarities with the gradual corruption of copyright over the years, extending it out into infinity (thanks Disney!), companies would rather hold close the things they refuse to use than give them to the people once they have no more profit to be made off of them.

I would like to see a graph of average second hand prices of different abandoned products over time. Mark the interesting points like apple not supporting the next version of the OS or blocking app downloads. Perhaps an income estimate of the average user at the interesting points could also be included and/or sales figures of still supported versions.