Hashicorp's stack, using Nomad as an orchestrator, is much simpler and more composable.
I've long been a fan of Mesos' architecture, which I also think is more composable than the k8s stack.
I just find it surprising an article that is calling for an evolution of the cluster management architecture fails to investigate the existing alternatives and why they haven't caught on.
Getting _something_ up and running quickly isn't necessarily a good indicator of how well a set of tools will work for you over time, in production work loads.
On the other side K8s was a steep learning curve with lots of options and 'terms' to learn but never was a point into the whole exploration where I was stuck. The docs are great. the community is great and the number of examples available allows us to mix n match lots of different approaches.
Things might have improved massively for Nomad since but I honestly have no desire to learn. Having used other Hashicorp tools since, I see them make the same mistakes time and time again.
Now I'm not the biggest fan of K8s either. I completely agree that they're hugely overblown for most purposes despite being sold as a silver bullet for any deployment. But if there's one thing K8s does really well it's describing the different layers in a deployment and then wrapping that up in a unified block. There's less of the "this thing is working but is this other thing" when spinning up a K8s cluster.