Any number of factors, such as the size of the type and the resolution of the monitor, complicate the calculation. Even double-spacing is a print vestige, undertaken to leave commentary and editorial space on a draft page. Commentary and edition in a digital text can just be inserted or executed wherever the reader wants. A paper written under the conventions of print is structurally different from one written for the screen. Even in the most concise style, there's room for lots of fat there.
Transitions alone take up significant space, usually stating precious little along the way.
I think it truly does. For those of us who have grown up with a remote control in our hands, the radically abrupt shifts upon the click of the button simply aren't a problem. In fact, the very notion of narrative itself becomes rarefied, a thing that we pick out from the noise, the conflicting voices, a distillation that may have nothing to do with linearity.