The problem with things like that is people will try to game it. People would just put a bunch of gibberish at the bottom of a page to raise the total percentag

The problem with things like that is people will try to game it. People would just put a bunch of gibberish at the bottom of a page to raise the total percentage of screen space. It reminds me of back in the pre-google days when sites would put tons of keywords in white text on a white background at the bottom of a page to try to rank higher.