It’s also not how eyes work because your visual resolution isn’t consistent across the field of view, saccades are a thing, etc. but it’s serviceable enough to get the point that you’re not just rendering a high-resolution scene but two of them requiring different processing for a fair chunk of the pipeline (consider how much geometry is only visible to one of them when you walk around a corner).

> And your explanation doesn't cover why the minimum number of cameras would be 12.

This is covered in the article. The key thing to understand is that there are multiple tasks using cameras: AR needs to track the world around you, you need eye tracking to handle saccades and conscious direction, and tracking hands, arms, legs, facial expressions, and body position accurately requires multiple cameras with enough parallax to build 3-D models which are accurate enough to generate realistic, stable imagery. People will really notice if things bounce around or deform or if you punt on some of the proven and end up with Meta’s leg problem.

The key point to take away here is that AR/VR aren’t one hard problem but a collection of hard problems which all need to be solved for most people to find the experience compelling — all with tight physical constraints.