As a case in point: I just set up a small new app on GKE. Because I'm experienced with Kubernetes, within a few minutes I had my app (a React front-end written in TypeScript and a backend written in Go) running and receiving HTTPS traffic. I entered just a handful of shell commands to get from an empty cluster to a functional one.
It's a cluster with a single node, no resilience. But this is genuinely useful, and a perfectly appropriate use case for Kubernetes. The alternative is the old way — VMs, perhaps with a sprinkling of Terraform and/or Salt/Ansible/Chef/Puppet, dealing with Linux, installing OS packages, controlling everything over SSH — or some high-level PaaS like AppEngine or Heroku.
While it's an example that shows that Kubernetes "scales down", I'm now also free to scale up. While today it's a small app with essentially zero traffic, when/if the need should arise, I can just expand the nodepool, add a horizontal pod autoscaler, let the cluster span multiple regions/zones, and so on, and I'll have something that can handle whatever is thrown at it.
My company has a ton of apps on multiple Kubernetes clusters, none of them very big. From my perspective, it's a huge win in operational simplicity over the "old" way. Docker itself is a benefit, but the true benefits come when you can treat your entire cluster as a virtualized resource and just throw containers and load balancers and persistent disks at it.