Why do members of the church of Jesus Christ of Latter-day Saints believe the priesthood keys and presiding priesthood were taken from the earth?

1) Not all apostles were killed, John an apostle who held Apostolic keys was granted "apower over bdeath, that I may live and bring souls unto thee. " according to D&Cov7 Joseph and Oliver use the seer stone and receive a vision of a parchment of John and given power to translate it that they may obtain an answer to their question. https://www.churchofjesuschrist.org/study/scriptures/dc-testament/dc/7?lang=eng

2) Paul teaches immortal church that the gospel of Christ Jesus would be upon the earth "throughout all ages, world without end." Ephesians 3:21

3) The letter of 1Clement (first century dated 80 - 140AD) says the Apostles themselves instructed the bishops and ordained them with power to call and ordain other bishops to retain succession and authority. 1Clem 44:1 And our Apostles knew through our Lord Jesus Christ that there would be strife over the name of the bishop's office. 1Clem 44:2 For this cause therefore, having received complete foreknowledge, they appointed the aforesaid persons, and afterwards they provided a continuance, that if these should fall asleep, other approved men should succeed to their ministration.

4) Brigham Young teaches robust quorum succession in the event of catastrophe (see Wilford Woodruff journal July 28, 1860) that if either the first presidency or the twelve or both are killed the seventy can recreate the church and can re-organize the higher quorums - which matches the letter of Clement.

Quote: "The President of the Church holds the keys of the sealing powers & his Council act in Concert with him [in] all things. Should the Presidency die The Twelve Could organize another Presidency & should the Presidency & Twelve all be slain the Seventies being Equal in power & Authority to the Twelve or first Presidency Could organize both Quorums. He also taught that a high priest is a primal seed and can re-organize the church if all authorities are dead (nuclear holocaust, alien uprising, voyages to new planets etc). Quote: "The High Priest Could organize the Church in all its parts if all other Authorities were dead for they have the Melchizedek Priesthood out of which grow all of the Higher offices of the Church."

5) John Taylor teaches of revelations received during the time of "darkness" which coincides with Ephesians 3

John Taylor, 7-Sept 1873 "Say some—'Oh, we are so enlightened and intelligent now. In former ages, when the people were degraded and in darkness, it was necessary that he should communicate intelligence to the human family; but we live in the blaze of Gospel day, in an age of light and intelligence.' Perhaps we do; I rather doubt it. I have a great many misgivings about the intelligence that men boast so much of in this enlightened day. There were men in those dark ages who could commune with God, and who, by the power of faith, could draw aside the curtain of eternity and gaze upon the invisible world. There were men who could tell the destiny of the human family, and the events which would transpire throughout every subsequent period of time until the final winding-up scene. There were men who could gaze upon the face of God, have the ministering of angels, and unfold the future destinies of the world. If those were dark ages I pray God to give me a little darkness, and deliver me from the light and intelligence that prevail in our day;"

Just to be clear I believe in restoration - these points arose as I studied the matter more closely when I served as a ward mission leader and the update of Preach my gospel released.

