> If they do support older machines and can’t guarantee perfect upgrades from every version operating system they’ve ever shipped, regardless of the condition of the user’s machine and how well (or not) the machine has been maintained, they’re also wrong.

Yes, a $50 billion company that doesn't run massive amounts of automated regression tests on one of its flagship products is Wrong. Come on, Microsoft manages to support absurd levels of backwards compatibility (see the discussion upthread about upgrading from Windows 1.0 to Windows 10), what's Apple's excuse?