The “many before him, and also ... many afterwards” in this sermon is not just a reference to believers, but to those who held this “holy order after the Son of God.” It it a reference to those who were made clean and pure by their repentance. It is those who, having been called by the Lord, chosen to this holy order, having their calling and election secure, hold power as a result of this relationship with God.
But none of these, before or since, (at the time of the writing by Alma) who held authority were greater than Melchizedek. As a result, he merited particular mention to identify those who held the holy priesthood after the order of the Son of God. It was merited because his example and his ministry illustrated perfectly what the “holy order” was intended to accomplish. It is designed to save others.
It was not to exalt the man.
It was not to bring attention to the man. It was not to amass praise or a following.
It was not to make the man a ruler over others. It was not to gain control or domination.
It was not to subjugate or force compulsive obedience upon the souls of men.
It was to serve and exalt those to whom he ministered. His greatness was derived by the fruit of saved, exalted souls whom he saved. There is no record of a single sermon preached by Melchizedek. We have evidence of the following things he did with his authority and power:
He served. He blessed. He produced exalted souls. He was not great by what he received, but by what he did with what he received to bless and exalt others.
You would know this if you understood the scriptures. You would not be following a false tradition wherein men are famous, celebrity-like, fawned over, held up to acclaim and given the authority to exercise control over men. This is a false model that the Gentiles follow, and not the way in which true priesthood holders operate. (Matt. 20: 25-28.) No-one possessing power from heaven will do this. (D&C 121: 36-37.)
Now, if you make this mistake and follow in this false tradition, it will be to your own destruction. Alma has warned you.
What a marvelously relevant book this Book of Mormon is for our own day! It is almost as if they saw our time, knew what we would struggle with, and had teachings designed to let us see the error and repent. I truly believe that we can get closer to God by abiding the precepts of the Book of Mormon than we can from any other book! Joseph Smith was right.