That's a more complex path I avoided discussing when I referenced CGroups. When I started doing these things kube clusters did not exist. These tips were for people using bare metal that have not decided as a company to go the k3/k8 route. Some of these settings will still apply to k8 physical nodes. The good people of Hetzner would be managing these settings on their bare metal that Kubernetes is running on and would not likely want their k8 nodes getting all broken, sticky and confused after a K8 daemon update results in memory leakage, billions of orphaned processes, etc...
Companies that use k3/k8's they may still have bare metal nodes that are dedicated to a role such as databases, ceph storage nodes, DMZ SFTP servers, PCI hosts that were deemed out of scope for kube clusters and of course any "kittens" such as Linux nodes turned into proprietary appliances after installing some proprietary application that will blow chunks if shimmed into k8's or any other type of abstraction layer.
I mentioned Hetnzer only because the original article mentions it. To be fair, currently it is harder to use than any managed k8s offering because you need to deploy your control plane yourself (but fortunately there are several project that make it as easy as it can be, and this is what I was referring to).
