This is also very true. The purpose of systems like Kubernetes/Mesos is to be set up once by a company, and for most developers to just interact with the CLI tool to run containers. Tools like Google Container Engine, make this into a software as a service product, where the cloud provider provides the API. In that world, as a developer, you never really think about the OS, just your app. But unlike in traditional PaaS, there is no framework that restricts what you can code (language, libraries, etc).