That entirely depends on your definition of "virtualization". I for one would completely consider all of the namespace support that docker/rkt/lxc use to be vir

That entirely depends on your definition of "virtualization". I for one would completely consider all of the namespace support that docker/rkt/lxc use to be virtualization. The reason being since the container has a different pid/network/mount namespace from the host, it is a "virtualized" version thereof. Now clearly this is different than traditional full operating system virtualization ala KVM/Xen, but it is absolutely still a form of virtualization. Just because something is different doesn't make it wrong.