As I get older, the more of a pain in the proverbial this becomes. Back in the day, when my Mac LCIII became unsupported after only 3 major releases (7.1, 7.5, 7.6) and 4.5 years, it felt kind of annoying but okay. I mean, 4.5 years was practically the same as forever when I was in my twenties. Nowadays, with fewer years ahead of me than I have in the rear-view mirror, time gallops by at a hell of a lick - and it seems iniquitous that support for a computer should be dropped after a mere six years. Especially when one of my main computers is celebrating its 12th birthday (Mac Pro, with Catalina) and another is celebrating its 32nd (Mac SE/30 with A/UX).
I have an IBM 5150 in the loft (original 5 slot PC to you), and that was supported for the latest versions of its primary OS (MS-DOS) for a conquering 13 years. Outside of mainframes and industrial use, can any other computer make such a claim?