Comment by drakythe

You answered your own question, its the bezel. They've gotten _much_ thinner since the 11 inch MBAs were a thing. Remember screen size is measured in diagonals, so even a 5mm reduction of bezel size both horizontally and vertically gains you a little over 7mm in screen size without a physical size increase. to gain 2 inches in screen size (50.8 mm) you'd only need to eliminate 0.74 inches (roughly) from all 4 sides. I don't know the exact measurements of the bezels on those older devices but I can tell you my M4 Air is less than half an inch on all sides.

EDIT: My math was bad. Its still not precise but its much more accurate now.