Diagonal lines are dynamic in time. Horizontal scribbles are static in time. Drawing a line under yesterday's low doesn't mean anything with respect to what is happening today.I would actually also disagree that diagonal lines are better than horizontal ones. The horizontal lines represent actual values that everyone can see, that aren't just a line made up like a diagonal one. As you say, diagonal lines can be drawn very many different ways, so this makes it arbitrary. But if you ask someone to draw a horizontal line under the previous day low, there is only one way to do this.
