Comment by wtallis

The ubiquity of mouse wheels and two-finger scrolling on trackpads drastically weakens your case for prioritizing the page up and page down behaviors in the scroll gutter. The mouse already offers a low-effort way to adjust scroll position at small to medium scales, generally much easier that repositioning the cursor from above to below the scroll thumb unless you really need to scroll by precisely one page (usually not possible on the web anymore because of floating dickbars).