> That said I also don’t think it’s a reasonable expectation for old binaries to continue to work indefinitely. Maintenance is a reality of life of a software developer, and personally speaking

There is a fine difference between keeping old binaries running and maintaining your application. I don't expect certain applications to be maintained, but I expect them to run on newer versions of OS for many years. If you think this is impossible, Apple can learn a lot from Microsoft and Linux. And IMHO, Microsoft didn't make unrealistic standards. One of the reasons why Windows has been the most dominant OS for years is exceptional backward compatibility.