The solution you mention is different from one that is described in the post. To make it happen you have to run VM, connect to it and modify the data on its (virtual) hard drive in a way that the relevant daemons or commands will be executed at start time including configuring `sysctl` and installing relevant binaries or scripts. Each time you need to change the behavior you will have to startup the VM, have the relevant startup script executed, then connect to the VM and modify the scripts.

The solution that is described in the post, the startup script is external to VM. You can modify it any time and make it run even on first launch of your new created VM instance.

Does it make differences more clear?