This is just silly. The article says the person doesn't want to turn their laptop into a server by installing the "openssl" package. So instead they run "docker", with another full server image inside of it. The "nginx" contains a lot of things not needed in this case, but conveniently has "openssl" installed.

And that's "lean and mean" apparently.

> You’ve created an SSL certificate using OpenSSL without actually running OpenSSL on the host system.

No, you still ran openssl on your host system, just in a separate namespace. It's docker, not a virtual machine.