You mean the Gibson choice of the 13 degree peghead angle? It creats a pressure of the strings on the nut. The greater the angle, the more the pressure and the better for sound energy transfer. But too steep an angle the neck will break easily. Gibson did experiment with different neck angles, but were not successful. I think PRS's have a 9 degree back angle on the necks, but they have longer scale lengths and can maintain the pressure needed on the nut.
No Mr. JL, just John or JL will do... I think the peghead angle is only one part of the formula in making a great and / or powerful guitar. With all other components, they combine to make a great Les Paul. For instance I think such a steep angle would not work well in a trem equipped guitar, even with the same scale length. john
Oh, I think I misunderstood you. Yes, what you said could be true. But there are too many variations in guitar design. An Ibanez RG guitar uses a spliced on headstock with a steep back angle, while a Fender would use string trees to maintain enough downward pressure of the strings on the nut. But I think we can be sure that certain pressure is needed for good transfer of sound energy.
There are some additional thoughts that I would like to provide. First, we need to define the meaning of "Powerfulness". Do you mean the "loudness" of the pickup that is due to higher output, or the "cut through" that is more an issue of overall design (scale length is the major factor). Second, as far as I know, either the angled peg head or the string tree have more things to do with the stability of the strings. The down angle of the strings passing the nut and the down angle of the strings passing the saddles should be the same. It will balance the tension of the strings, which makes the strings vibrate more evenly. Under this circumstance, the vibration sustains better and are more in tune. Third, guitars with bolt-on construction and longer scale generally have higher tension that causes "stiffness" when you play; however, the tone cuts through better. It explains why stratocatsters and telecasters can be heard clearly in a loud situation even though they have single coil pickups. On the contary, Les Paul (set-neck construction) in shorter scale (24-3/4") is often criticized on the muddiness of the tone that is associated with this design, even though Les Paul has higher output humbucking pickups. Paul Reed Smith has scale length in 25" that improves the "muddiness" problem that is often inherited from Les Paul type of construction. Just for your information