No I don't think he meant that. I know countless numbers of users that are familiar with the Docker cli and exactly 0 of them that know how to manipulate kernel namespaces, cgroups, lxc, etc. manually. Not a thing in the developer community. Docker is what makes that stuff useful and usable. As low level primitives they are fine but they'd never be used that widely without something like Docker. Clearly they depend on each other but they are not the same thing. Also there's more to Docker than just that. E.g. the layered filesystem is hugely important.