Earlier quoted context omitted.
Docker is a genius idea which looks obvious in retrospect, but someone need to invent it. Docker is more than just chroot. You also need: overlay file system; OCI registry and community behind it, to create thousands of useful images. And, of course, the whole idea of creating images layer by layer and using immutable images to spawn mutable containers. I don't actually think that you need network or process isolatio…
What I always wondered is why qcow2 + qemu never gave rise to a similar system, they support snapshots/backing-files so it should be possible to implement a system similar to docker? Instead what we got is just this terrible libvirt.
Dockers is conceptually simpler for devs and the layer use case but has huge performance issues which is why it never went anywhere for non-docker classic IT type use cases.