I'm pretty sure that a VM gets abstrations of the underlying hardware. And these abstractions are fully documented and as such the generic drivers bundled with any linux distro will work perfectly with it. Running on actual hardware requires hardware specific drivers. Generic drivers exist for many types of devices, but they might not be able to fully use the hardware (or at all), which can lead to some features/the os to not work out of the box on linux distros.

And I assume that he refers to that emacs is the default $EDITOR var on ubuntu? I don't know if that's true, but i think emacs is one of these editors which is seen as having very bad usability. I can't imagine that emacs is the default $EDITOR on a recent ubuntu version, but I agree with the sentiment that those kind of editors should never be the defualt.