Formations for blocking field goals

Question
I'm not familiar with the rules regarding positional requirements for the defense during field goal attempts. My question is why can't the defense use like a catapulting like move where the tackles crotch done and someone from the backfield jumps over them to block a field goal. Almost like jumping on there backs and stopping the ball. If this is illegal could you please explain why. Thank you

Answer
Jason
Rule 9 specifically prohibits this type of act for blocking kick.  The action you describe was used nearly 100 years ago and was deemed too dangerous for the game.  The rules now prohibit the defense from "running leaping and landing on any player" in an attempt to block a kick. Also the rules prohibit a player from using another player for leverage to gain height on a play to block a kick.  Specifically the rule prohibit the stepping on, jumping on, lifting of a player to gain leverage or height.  The reason the act is illegal is because the rules committee over the years has found it to be too dangerous and injuries resulting from these acts.  Also it felt the stacking of player above a single player's own height was an unfair act in contempt of competitive sportsmanship.