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.
Actually, this is I think where you are quite wrong and something that I can confidently say through my own testing. On many days, price will often turn at an overnight high or previous day high, or overnight low, or previous day low. This tells me that lots of traders are aware of where price turned before, and they nobody wants to pay higher, or sell for lower again. The fact that these are static as you say makes it less arbitrary because there is no way to change this number, no way to "get it wrong". Now it of course does't happen all the time, but I can say with much confidence that price levels along the horizontal make for excellent trade opportunities.
When drawn according to DbPhoenix's clear instructions, they will all be drawn identically so long as the scribblers are using arithmetic scale.
Has ET been screwy for anyone else this weekend? When I pt the above post together, the last visible post was B1S2's, and then I hit enter, and I see I am very late tot he party. I wouold delete mine, since DbPhoenix already posted the same charts, but I think that those instructions cannot be repeated enough, so I will leave them, and likely repeat them as necessary.