I think Chris is talking about tilt only, not pan and tilt. Tilt only for monopod is based on the idea that a full ball head can be harder to control since you are holding the camera with one hand and loosening the ball head with the other the ball head can flop fully to one of the sides and cause problems. That is why I use the bowl (leveling) head, it only has about 15 or 20 degrees of motion in each direction so gives you most of the flexibility of the ball head without the possibility of flopping the same way. It also can be set to hold its position but also be loose enough to change position when I want it to. That helps when panning with the leg out in front, that can be a little more award with tilt only if the leg is off center.