Yes, it’s the future, but as I mentioned, the Mac I’m running High Sierra on is nearly 10 years-old—it shipped with a version of Snow Leopard, MacOS x 10.6.
That was 7 major operating system releases ago—pretty sure nobody at Apple tested upgrading from an operating system that hasn’t been supported by Apple in many years, not to mention all of the permutations of hardware, kernel extensions, file systems, 3rd-party software installs, etc.
This is the double-edged sword: no matter what Apple does, they’re wrong. If they don’t support older machines with the latest operating system, then it’s a conspiracy to force its users to upgrade.
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.
Yeah, I'm an idealist. Sue me.
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?
You do realize, don't you, that if this is a relevant question I already have cause to complain? It's been the future for some time now, give us reliable upgrades already.