Remember the game of Red Rover? What is the value of having two strong people stand next to each other?
*Where would Satan try to run through?
*What advantage would there be to having a strong person holding hands with those who were not so strong?
President Boyd K Packer: Peter was to hold the sealing power, that authority which carried the power to bind or seal on earth or to loose on earth and it would be so in the heavens. Those keys belong to the President of the church - to the Prophet, seer and revelator. That sacred sealing power is with the Church now, nothing is regarded with more sacred contemplation by those who know is more closely held. There are relatively few men who have been delegated this sealing power upon the earth at any given time. In each Temple are brethren who have been given the sealing power. No one can get it except from the Prophet, seer, and revelator and President of the Church of Jesus Christ of Latter-day-Saints.
How can the sealing power "weld families together so that Satan can't break through and destroy them?
Behold, I give unto you power, that whatsoever ye shall seal on earth shall be sealed in heaven; and whatsoever ye shall loose on earth shall be loosed in heaven; and thus shall ye have power among this people.