Managing a cluster is the tricky part of k8s but just running your stuff on an existing cluster is extremely straightforward. I could definitely see the attraction of a cheap managed k8s cluster with a single node. Maybe hosted k3s or something.
After your single cattle is murdered, the next one has to be raised right?
State has to come from somewhere. Downtime has a cost for most businesses.
Kubernetes just makes that story so much simpler. Heck a good cloud provider can just handle any machines fucking up automatically without any human intervention on your side.
The same can't be said for a single machine.
But being able to blow away a k8s node and bring it back up in 2 minutes (or have k8s auto-spawn a replacement node) is WAY faster than having to reinstall wordpress, reinstall nginx, set IP addresses, fiddle with your DNS, restore a database from a backup, etc, etc, etc.
A car is a hugely complicated machine and I'm sure in the 1910s people said only some people will ever need them. Bad analogy considering cars kill lots of people but take that part out :)