(Full disclosure, I'm the author of the Medium post.)

It's essentially the way Docker for Mac works, though Docker for Mac has far more mature tooling these days. Before the switch to macOS's native Hypervisor.framework, it was very much running VirtualBox with a Linux VM as a "shim" if you will.

For local dev work it scratches an itch for me and maybe for the minority of folks wanting to use OpenBSD as their workstation OS. ("There are dozens of us. Dozens!")

Plus it's just fun to play with VMM. :-)