Other people also mention that the-boxes-that-turn-blue don't track what they're actually reading very well. And the reading speed doesn't take into account tha

Other people also mention that the-boxes-that-turn-blue don't track what they're actually reading very well. And the reading speed doesn't take into account that people pause and think. Or that they might pause and write a reply. I suppose the-blue-boxes-approach would work only with mobile phones, where only one comment is shown at a time. (I haven't thought much about it, but I think I tend to keep the mouse pointer just anywhere.)