Sighted users get that from visually scanning the page. The display is two dimensional with colors and images. So it is sort of two-plus dimensions. Speech is one dimensional. We can add voice changes and pitch changes, just as color is added to the screen.
Voice changes kind of make it one-plus dimensions.
It is easy to get lost on the Web. It is much easier to get lost with a one dimensional view of a two dimensional universe. So there is a fundamental difference that the self voicing browser has to accommodate. Web Authors can help Comfort is an important part of browsing the Web with speech. If you can see, you train yourself to ignore pictures and navigation links going down one side of the page - you get familiar with the visual layout.