I think you missed the part of the parent comment where it says "change the entire focal depth of the display to keep it always in focus". What you have described is how VR headsets currently work, and the entire problem the parent comment's proposed system addresses.
I'm not explaining very well then. Current VR headsets are only in focus at a single focal length. I'm describing a display that would magically be in focus at every possible focal length. The lenses would respond to your eye's current focal depth to keep the display always in focus, no matter how near or far your eyes are attempting to focus.
Crossed wires? I was replying to noio, not you. Your first post was quite clear enough. For what it's worth, I think it's quite a good idea.
Since my entire contribution to this thread seems to be to gently correct people who did not read the comment they're replying to carefully enough (a regrettably frequent occurrence I'm sure I'm guilty of myself from time to time), I would like to take this opportunity to exhort the HN community to please make it a habit to reread and attempt to a understand a comment before replying. It's a luxury we don't have in spoken conversation, so let's make it count here.
Also, by the way, you can edit posts; it's better to do this than clutter up the thread by replying to yourself.
I think this might also help a bit with edges of the display not being in focus assuming you also had eye tracking. You could always be sure that the center of your gaze was in focus. You'd still have issues with the edges of vision being out of focus, asymmetrically at that.
