The point about maintenance is a good one if you're running purely static sites. K8s has a steep learning curve, though FWIW I think its probably easier than systemd and standard unix administration + puppet/chef/ansible/etc.
I agree with your second point, too. If you don't view K8s as something you need to know _everything_ about, it's a powerful tool that simplifies things that you'd need multiple tools for. I never really learned provisioning tools like Puppet/Chef/Ansible and Systemd, so k8s was a fresh experience for me. I like it, though, because I really like containers over VMs as the unit that's running my code.
That is, if you really want managed kubernetes. Otherwise you can get a $5 VM on DO.
For something really simple, sure. For something that goes beyond a simple web server, you might be touching on similar competencies to those needed to run your services "the old way"
It might be easier to manage, sure, but to get started, and have an efficient deployment, not necessarily
Examples: your system needs a special service or library that is not available in the distro, you need to deploy a cronjob or similar periodic service, you need multiple services running at the same time (either in the same pod or separately), etc