12 men in the huddle

Question
Is the purpose of the 12 men in the huddle rule so that he defense can anticipate the formation of the offense?

Answer
 Benjamin
In a sense, yes.  But first, the rule does not prohibit 12 players in the huddle, it prohibits 12 from breaking the huddle.  The purpose of the prohibition 12 players braking the huddle is so there is no deception in the substitution process; using the substitution process to confuse opponents is a foul.

Team A can not break their huddle with 12 of more players.  This is a dead-ball foul. A departing player who leaves the huddle or his position within three (3) seconds is considered to have left immediately.

Here is the rule: Rule 3-5-3

More Than Eleven Players on the Field
a. Team A may not break the huddle with more than 11 players nor keep more than 11 players in the huddle or in a formation for more than three seconds. Officials shall stop the action whether or not the ball has been snapped.
b. Team B is allowed to briefly retain more than 11 players on the field to anticipate the offensive formation, but it may not have more than 11 players in its formation if the snap is imminent. Whether the snap is imminent or has just occurred, the officials shall stop the action.
PENALTY--[a-b] Dead-ball foul. Five yards at the succeeding spot.
c. If officials do not detect the excessive number of players until during the down or after the down is over, the infraction is treated as a live-ball foul.
PENALTY--Live-ball foul. Five yards at the previous spot