When rotating objects (particularly cards) they it would be nice if they just rotated rather than rise, rotate, then fall. When there are other objects on top of these cards those items pass through the card when it rises and will now be under the card after it falls. This makes placing counters on top of cards undesirable as they'll often end up under the card they are on. The idea here is to have a counter on a card which will stay on top of the card without moving. Joint doesn't quite take care of this as you can't then move or rotate the counter (or dice) if you need to without removing the joint.