Space was limited and the mechanics of writing was difficult for Mormon. Therefore, in his abridgement of the account, for all others "the Lord called," and the ceremony was repeated for each. In the process, He "said likewise" unto each of them. Every individual person was acknowledged by the Lord as having conferred upon each of them "power to baptize" by the Lord.
None of those who received this power had any doubt about their authority to act in this ordinance in the Lord's name. None of them lacked the "power" to baptize others. None of those who were present, and still kneeling during the ceremony, or who overheard the Lord's words had any doubts about those who held a commission from Christ to baptize them. Finally, none of those present would have any doubts about the need to be baptized by this newly bestowed power.
Although every one of them had been baptized previously, it becomes apparent that once new power to baptize has been given by Christ, that power ought to be used. It is not given to be neglected. Nor can power endure through neglect. So when given, the power is to be used, and all who were present are candidates for baptism.
Then comes the instruction from Christ as to the manner for performing the ordinance. "On this wise shall ye baptize..." begins the instruction. If the Lord provides the power and then gives the instruction, can the ordinance be changed? What if someone else says they hold the keys, and we all accept the person does in fact hold the keys, can such a person change the manner of baptism? If there is a potential convert who is infirm, ill or elderly and is unable to be baptized in the prescribed manner, can the ordinance be changed in form to accommodate the need? That is exactly how the ordinance was changed after the New Testament times. A reasonable need, and accommodation for that need, resulted in an exception. Then the exception became the rule, and the original manner was forgotten.
If the Lord's instruction regarding the manner of baptism in this verse cannot be changed, even by one holding keys and authority to do so, then what about other ordinances? Can other ordinances be changed by one who holds keys if they choose to do them differently? Why not? What happens when the one in a recognized position to perform ordinances decides to make changes to the ordinances?
Assume for a moment the Lord instructs Nephi on how to perform baptism, but Nephi decides thereafter to make a change to it. How would that reflect on Nephi? How would that reflect on the Lord? How would it reflect on the Lord's instruction? What about Joseph Smith's statement: "Ordinances instituted in the heavens before the foundation of the world, in the priesthood, for the salvation of men, are not to be altered or changed." (TPJS p. 308) If the Lord gave Nephi the "power" to baptize, does that carry with it the "power" to change it as well?
Well, the purpose behind the Lord giving instructions was that "there shall be no disputations among you." Does the instruction given by the Lord end as soon as we begin to see "disputations among" followers? Can an opinion poll that shows a majority of those who practice the ordinances don't relate to them anymore and want to see them altered, create a "disputation" that allows the instruction from the Lord to be altered?
As stupid as these questions may seem, there are people who are genuinely confused by them. So I ask them. You must decide if the Lord's instructions deserve respect and ought to be followed. Apparently men of good faith, honest hearts, and sincere desires can by reason of their status alone, contradict the Lord's instructions and people won't even blink. That's the beauty of the claim that Rome makes to having Peter's keys and the ability to seal on earth and in heaven. The Catholics can change anything and no one doubts they had the authority to do it. To allow the possibility that God would not support the Pope would be to entertain the unthinkable. So don't even hold that thought.