...Does any other popular consumer OS get that level of support?...
The real question is: does any other popular consumer OS need that level of support?
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If Microsoft did not mess up the "next version" as much as they have done, there wouldn't be the need to stick with a particular version for so long.
As an alternative case in point, my three Windows PCs tend to stay with a version until that version is no longer supported. While my single Macmini has had the OS upgraded to the newer version a few times, and all at no cost or bad experiences to me.
With the Macmini, the OS upgrade to the next version has been a fairly smooth experience, as opposed to a Windows OS upgrade to the next version which is more of a traumatic experience.
Maybe that is the cause to the need to have long support cycles for Windows OS versions?