What this have to do with reliability of windows as a platform. Reliable platform means, that new versions of OS do not break your old program. Which is true f

What this have to do with reliability of windows as a platform. Reliable platform means, that new versions of OS do not break your old program. Which is true for windows. Of course, as OS becomes more capable, it's possible to write programs that can't work on less capable older versions. But even then, windows tries to add fallbacks so that most new programs still work on old versions.