In addition to stopping driveline destroying axle wrap and wheelhop, the purpose of a traction bar is to use the rotational forces of the rear axle to help transfer lift to the front end to aid in weight transfer back to the rear wheels. It does this by applying that rotational force to a point in 'front' of the rear axle - the further forward that point of transfer is (long bars anyone?), the better the 'lift'.
If it's only job was to stop axle rotation and cure wheel hop - it could easily do it by clamping BEHIND the axle
Don't be fooled by this picture! In both cases, there is no leaf spring shown . So how can you compare the two? Tractionbar picture is not gonna be able to "push" along it's centerline because the leaf spring won't let it ! So the real forces are much the same . To each his own i guess . The picture is. Learly for marketing the ladderbar! ......just my 2 cents