I'd argue that I was able to do the exact same thing 20 years ago using VMWare Workstation - download a VHD image with OS and app(s) pre-installed and configured, optionally map to a drive on the host OS and get started instantly...
Maybe I'm too old to get the appeal of "a fleet of containers" in place of a single (and potentially throw-away) VM image along with maybe even a vagrant-script to make it easily reproducible... ¯\_(ツ)_/¯
Running multiple containers is faster and more efficient than multiple VMs. Running a container on the same kernel as the host is faster and more efficient than a VM. If you're trying to run an app across different OS kernels, you still have to use a VM unless you can compile your app on that kernel natively. This project really doesn't do much beyond what a VM gets you, and you still have to configure the host outside the container to enable virtualization.
Yeah, tooling/workflows are the (possibly only) reason that Docker is popular. It's like how the FreeBSD folks will say that they've had containers (jails) long before Linux, which is true but misses the point that without the ability to pull and run images trivially they're losing, badly, on usability.
Maybe I'm too old to get the appeal of "a fleet of containers" in place of a single (and potentially throw-away) VM image along with maybe even a vagrant-script to make it easily reproducible... ¯\_(ツ)_/¯