Why do you think all joints in the human body are not all ball-and-socket joints?
Ball and socket joints allow for a circular range of movements. However, they require specialized sets of muscles to control them well. Additionally, ball and socket joints tend to be weaker than hinge joints due to the need for additional muscles to properly control a ball and socket joint. Despite the possibility of giving us hilarious amounts of flexibility if all our joints were ball and socket, it would require inefficient sets and amounts of muscles, and this means less muscles in places where it would count, like in our legs to walk or arms to lift. Besides, we’d probably get all tangled up on ourselves during intercourse.
