Because you can't get the wheel off if you lower around 2 splines or more? That the only benefit of the adjustables that I can see. You end up using them more or less as straight plates, moving them around the splines to get the rough height so they remain straight. But they have a hinge in the middle to let the wheel drop out of the arch when you disconnect the bottom of the shock. Essential bit of kit IMO, but not needed for 1 spline.