I learned of this working at Apple that they don’t really strive for backwards compatibility. I think I upgraded some internal tool and discovered this MO. This

I learned of this working at Apple that they don’t really strive for backwards compatibility. I think I upgraded some internal tool and discovered this MO. This was in such a contrast to Microsoft where I heard crazy stories of incredibly old software still being able to run. What exactly is the overhead to achieving such astonishing backwards compatibility as Microsoft has?