Backward compatibility is offered by some professional environments. For instance, AIX guarantees backward compatibility, old 32bit or old 64 bit programs have to work on the new AIX releases. Of course, some features coming with the new processors will not be available, some facilities offered by new processor instructions are not present in the old programs, but they are certified being able to work without recompiling on the new operating system releases.
My personal opinion is that backward compatibility between recent versions of windows should always always be present. Like when windows 8 came out, it should have been completely backward compatible with windows 7 programs. But that's how I think, and certainly microsoft's professional don't think similarly.
And, unfortunately, this is not the case in the PC world, where drivers for the old hardware are not available on the new windows versions, and even old programs are not compatible with the new operating systems.
Same thing for me. So, my Win95 computer is not often powered on, and my winME computer is still used.
I have this trend of buying one thing and then holding on to it as long as it works.