This only works if your environment is bare metal to begin with. In some cases you may be in an environment where a lot of applications are proprietary, virtualized, or otherwise constrained in some other way. It is not an environment where you get to pick and choose how everything is setup. In such a case, having a distinct small application that fits as "an OS" in a virtualized environment can fit a lot better in, than trying to retrofit a baremetal containerized environment into a large enterprise datacenter where everything is already running Windows servers and proprietary services, managed by other people than yourself.