Conjunctions are also used in the Book of Mormon in place of where we would usually expect parentheses.
From John A. Tvedtnes
Another difference in the use of conjunctions is that in biblical Hebrew, a language with no punctuation, the conjunction also serves as a marker of parenthesis. The words we would put inside parentheses in English are preceded by the conjunction in Hebrew, and, at the conclusion, the next phrase is introduced by the conjunction. In the following biblical example, the same conjunction has been variously rendered and, for, and that by the King James translators to fit the requirements of the English language: “As they that bare the ark were come unto Jordan, and the feet of the priests that bare the ark were dipped in the brim of the water, (for Jordan overfloweth all his banks all the time of harvest,) that the waters . . . stood and rose up” (Joshua 3:15-16). We see that for and that, two English renditions of the same Hebrew conjunction, served to set off what the English translators chose to mark with the parentheses.
The Book of Mormon also uses conjunctions to mark parenthetical phrases. In the Book of Mormon examples listed below, I have added parentheses to illustrate:
“After I, Nephi, having heard all the words of my father, concerning the things which he saw in a vision, and also the things which he spake by the power of the Holy Ghost, which power he received by faith on the Son of God (and the Son of God was the Messiah which should come) and it came to pass that I, Nephi, was desirous also that I might see, and hear, and know of these things” (1 Nephi 10:17, reading of 1830 edition).
“When Jesus had spoken these words unto Nephi, and to those who had been called, (now the number of them who had been called, and received power and authority to baptize, was twelve) and behold, he stretched forth his hand . . . ” (3 Nephi 12:1).– John A. Tvedtnes – The Hebrew Background of the Book of Mormon
In addition to everything else Joseph Smith would have needed to remember while dictating the Book of Mormon, how would he remember to use conjunctions this way?