I might have misunderstood you but there is a huge difference between a developer being able to use docker and understand the basics of containerization and CI/

I might have misunderstood you but there is a huge difference between a developer being able to use docker and understand the basics of containerization and CI/CD, and a devops/ops person managing servers/clusters using docker swarm or kubernetes. The latter of the two is so far more difficult to master than the first. Managing a kubernetes cluster has so many possibilities to shoot yourself in the foot without realizing it. There are dozens of tutorials online how to set up a simple linux/nignx/python/postgres cluster (including lots of results for common error google searches) while routing problems of your legacy php application that is behind an istio controlled ingress running on a specific kubernetes version will leave you for yourself. Sure you won't be able to scale indefinitely. Switching a solid containerized project running on your self-managed machines to a kubernetes setup will be quite easy (if you heeded devops best practices).