Let's say you have an Ubuntu OS in Virtualbox, and an application is running "on top" of Ubuntu. Now try swapping out the Ubuntu OS for Windows without affectin

Let's say you have an Ubuntu OS in Virtualbox, and an application is running "on top" of Ubuntu. Now try swapping out the Ubuntu OS for Windows without affecting the application. It's nonsense, because an application only works when there's an OS to provide an abstraction layer for talking to hardware. Of course, there are applications that run on bare metal without that abstraction layer, but the point I'm making is that in stacks with an OS, an application "on top" of that OS is not independent of the OS even with virtualization.