I din't get why you would need glasses for vr if you are nearsighted. In that case you would only need help seeing things far away sharply. But the lenses are right in front of your eyes. So how is that a problem? On the other hand I always presumed that farsighted people would have a problem since they cannot see stuff near them sharply. Svennoj, you said it is about the focal point of the lenses?
The ELI5, the lenses refocus the light from the screen, so that it appears to be ~2m away.
Basically different shapes of lenses change where the light converges. Your eye changes shape a little bit if you are looking at far away objects or near objects.
Even though the screen is ~2 inches from your eyes, it refocuses the light so that it converges at ~2m.
If you're looking through a focused lens, your eyes basically need to match the lens.
Some of the VR headsets were supposedly focused at infinity. As I said before, most of the current ones as far as I'm aware, are focused at around 2 meters. Not exactly sure what the reasoning for that is. Probably a combination of reducing eye strain, and probably that it's a good fit for physical movement. It's about 2 arm lengths away.
As SvennoJ mentions, there is new tech on the horizon that would allow the headset lens to change focal length.