SRE here, when most people say "Server Management" they are talking the root of their problem. "I have this set of Applications and that need to run on this fleet of servers. How do I do this?" and Kubernetes is commonly the answer but not only answer.

Yes, you still need to something to "install" the Kubernetes but that is generally easier surface area with something like Talos OS, K3s, whatever Canonical/Red Hat cooked up.

Kubernetes is only another application to me, it just manages containers (which probably run applications, which may be serving something, I guess?). Definitions have got a bit muddy since the advent of devops imo! (Maybe part of the weirdness is that this post is about an app that manages crons and files and other os-level stuff)