Earlier quoted context omitted.
They're not flipping a kill switch on these devices. They just won't be running the newest OS. I don't see how these two things (software updates and hardware longevity/recyclability) are at all related.
The main issue is, as the article points out towards the end, that you only receive all macOS security updates if you are on the latest major version. The two major versions prior to that one receive some, but not all, security updates. Once you are three major versions behind, your Mac does not receive any macOS security fixes anymore, which of course is hugely problematic. So yes, unless you are completely ignoring…
Also, if security is your #1 priority you should pay the cost of the upgrade. Monterey is compatible with Macs as old as 2015. That means that Apple will sunset security support for it in 2024. That's nine years of supported life for your computer – not bad.