Well, they work...?
If you stick your rod in the water and look at it from an angle, your rod looks bent (due to refraction and the light bending)
Maybe the surface indendation does the same from underneath, so the ball isnt that visible.
I agree with you but the same thing can be said about klinkhammers and a green hackle stalk etc. They work fine.
Maybe better than a suspender buzzer as the hackle distorts the water more?
I'd be more worried about the fish rejecting the large curvy hook bend shape sticking out the insectss butt. But the fish dont seem to mind them