score:5
Because the the Father gave the world His Son (Isa. 9:6, John 3:16).
It is the doctrine of Christ (3 Nephi 11):
35 Verily, verily, I say unto you, that this is my doctrine, and I bear record of it from the Father; and whoso believeth in me believeth in the Father also; and unto him will the Father bear record of me, for he will visit him with fire and with the Holy Ghost.
36 And thus will the Father bear record of me, and the Holy Ghost will bear record unto him of the Father and me; for the Father, and I, and the Holy Ghost are one.
The Father is glorified in the Son (John 14:13, 3 Nephi 9:15, D&C 76:43). Selecting 3 Nephi 9:15 here:
15 Behold, I am Jesus Christ the Son of God. I created the heavens and the earth, and all things that in them are. I was with the Father from the beginning. I am in the Father, and the Father in me; and in me hath the Father glorified his name.
The Father is the second witness to that of the Holy Ghost of the divine sonship of Christ, and by two or three witnesses shall every word be established (Matthew 18:16).
The principle in the Priesthood of delegating responsibility may be part of the reason as well. The Father does this several times, including committing judgment to His Son (John 5:22):
22 For the Father judgeth no man, but hath committed all judgment unto the Son
In almost every case in LDS theology, God the Father introduces His Son, who is our Mediator and Advocate to the Father.