I personally don't know and can only suppose that at some level of the game(not the highest, but another leagues) there is no must for the team to have a libero and some of them choose not to have such a player. What do you think about it? I expect your opinion because I'm very interested in this question!
A libero is a defense specialist in volleyball and their main job is to pass the volleyballs and pick up hits in the back row. To be a libero, you would need to be defensive, and accurate passer and willing to dive for the ball.
A libero is a player that specializes in passing the ball. This position is for those who are very good at passing and defensive strategy
1998 saw the international introduction of the defensive libero player to the sport of volleyball.
A libero tracking sheet is used in volleyball to mark down when the libero comes in and out of the game and who he/she goes in or out for.
Yes, the libero can set. However the libero may not block, attempt to block, or serve.