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 the security of your system, losing macOS support is a kind of soft kill switch for the hardware.