4:3 does happen, just coincidentally, to damn-near match the aspect ratio of a 2-page spread on a comic, too (~1.3 width/height on an open comic book, 1.333... for 4:3, 1.6 for 16:10) which means a larger screen in a wider ratio might not actually be any benefit (or not enough to justify the extra weight/unweildiness, perhaps) for that particular narrow use case.

Which, it's a very niche and specific thing, but still, if we're talking "what's the very best device for that exact thing, disregarding all other concerns", having a 4:3 screen ratio's an advantage over all the other common ones.