But I think the author then translated that to mean that Kubernetes is also difficult to use. It's much easier to use than it is to install.
On the flip side, when I had started seriously using Docker, I quickly ran into it's limitations. Docker is easy to use... as long as you stayed within the playground. When I started using Docker Compose seriously, I quickly ran into problems it couldn't handle. This was about 12 months ago. I think the current networking and docker swarm expanded that playground ... but it doesn't bridge the gap into getting this out as reliable and resilient infrastructure.
Docker seems to go for solutions that are general and flexible whereas kubernetes is very opinionated.
I'm not so sure that Kubernetes is being opinionated. They sit higher in the stack, and yet, it is built as a collection of building blocks.
Chances are, what Docker Swarm will turn into is reinventing Kubernetes.
I don't think the direct complaint was that Kubernetes didn't "run in containers" but that it isn't as easy to set up as "just running some containers".
"With Docker we were supposed not to have installation instructions (aside from a few docker run arguments)". He was saying that the Kubernetes setup didn't fit the ease of setup touted by Docker.