Maybe you should read the article? The article basically covers running a tiny kernel that as exactly what you need to run one single binary, which is your application. No printer drivers, video drivers. Probably have network drivers, as that would be quite handy. Kinda up to you on what kernel you pick for this, and what drivers are included. Multiple VMs with networking can also be "combined"...

Containers are great because they are small and fast, low overhead etc. And that is why they replaced virtual machines. This article however proves that this is also achievable with virtual machines.

VMs don't need a full OS. You can run a single process directly from the kernel with no init system or other userland

VMs can have private networks between each other just as containers do. That's pretty much what EC2 is about.

heck, when running something in production with multiple underlying servers, you need a system that builds an overlay network regardless if you use containers or Vm's..