You can still run an older kernel. There are the "Super-long-term support" releases that have 10+ year support cycles. Some distros may go even further.
If you install 6.12 today (via e.g. Debian 13) then you'll be good until at least 2035. So removing it now de-facto means it will be removed in >10 years.
And as the article explains, this mostly concerns pretty old systems. Are people running the latest kernel on those? Most of the time probably not. This is really not "running after the last shiny thing". That's just nonsensical extreme black/white thinking.
That's assuming your old machines will never need to interface with new peripherals or new network protocols or new filesystems or anything that could require changes only found in newer kernels. It's not far removed from saying that Windows still supports them as well because you can always use Windows ME for the rest of the millennium.
Won't these super old kernels basically turn into forks after some time that are maintained and even extended for special purposes?