You only need the clarity the eyes can actually perceive. What physics do you think prevents this? There are already headsets with 70ppd [1], which is the same as a 27 inch 4k display, 23 inches away. That’s now.
Sorry, I was referring to the parent comment's notion that the headsets would be as "easy as wearing glasses" and have high quality (especially color fidelity), not that you can't have high quality VR overall.
Why can’t they be as easy as wearing glasses [1]? Do you think direct retina projection (also available now) is somehow limited? I agree waveguides might be.
1. https://varjo.com/products/xr-3/