> Intel Coffee Lake and AMD Zen+ came out around 2017/2018, that's
5 to 6 years ago.
You're (probably unintentionally) exaggerating, but that's not how it works. When a new CPU comes out, all the machines on the market don't magically replace their CPUs with that one on day 1. The machine I'm typing this comment on right now was a pretty high-end one I got after those CPUs came out, and its CPU is from an older generation. In fact, I don't even recall having seen machines with newer CPUs on the market (at least not with the minimum specs I was looking at) until quite a few months later, though my memory might be hazy here. Sometimes the price points are also a factor here too.
> those Coffee Lake and Zen+ systems (let alone older) are coming due for replacement/upgrade soon for anyone inside of a lifecycle cadence whether Windows 11 demanded it or not.
That's by no means universally true; there are plenty of good machines out there that work just fine and that people want to keep using. Again, speaking from personal experience, I know my machine is perfectly good and I hope to keep using it for several more years. An older one I had from several years before that, which I gave away for unrelated reasons, was also great, and I would still use it if I had it and my current one somehow broke. There's been literally no reason for me to throw these away anytime soon other than Microsoft forcing me to. Lots of people are being forced to throw away perfectly good hardware because Microsoft/Google/Apple/etc. force them to, often via software.