Until very recently, I'd have included myself in that camp.
After several months of focusing on finding examples of internal consistency, my attention to the care that went into producing this text was at an all-time high. As a result, my interest in attempting to understand the purpose of the intertextual connections was piqued.
I'm certain that I could spend the rest of my life studying this subject and I'd still have more to learn in the next life.
In this post, I'm going to attempt to flesh out an idea that has formulated in my head over the past few weeks. Like many other ideas I post on this blog, this one is raw and still very much a work in progress.
To put it simply, I believe one of the purposes of the intertextuality between the Book of Mormon and other scriptures is to symbolize the gathering of God's word in the latter days. It is a metaphor for the gathering of Israel. If the Book of Mormon is the instrument of gathering, then it is only fitting to have its words taken from many other scriptures throughout the history of mankind. What better way to lay out the case that God's promises will all be fulfilled than to bring about that fulfillment by means of a book which contains a carefully curated compilation of God's words to prophets throughout the ages?
I'll illustrate the careful attention these words deserve with a clever example of intertextuality between the sermon of King Benjamin and the Revelation of John.
First, Benjamin's description of the judgement which the words will bring upon those who do not give heed to them:
23 And now I have spoken the words which the Lord God hath commanded me.
24 And thus saith the Lord: They shall stand as a bright testimony against this people, at the judgment day; whereof they shall be judged, every man according to his works, whether they be good, or whether they be evil.
25 And if they be evil they are consigned to an awful view of their own guilt and abominations, which doth cause them to shrink from the presence of the Lord into a state of misery and endless torment, from whence they can no more return; therefore they have drunk damnation to their own souls.
26 Therefore, they have drunk out of the cup of the wrath of God, which justice could no more deny unto them than it could deny that Adam should fall because of his partaking of the forbidden fruit; therefore, mercy could have claim on them no more forever.
27 And their torment is as a lake of fire and brimstone, whose flames are unquenchable, and whose smoke ascendeth up forever and ever. Thus hath the Lord commanded me. Amen. (Mosiah 3)
Compare this passage to the following two clusters of verses from two different parts of Revelation:
10 The same shall drink of the wine of the wrath of God, which is poured out without mixture into the cup of his indignation; and he shall be tormented with fire and brimstone in the presence of the holy angels, and in the presence of the Lamb:
11 And the smoke of their torment ascendeth up for ever and ever: and they have no rest day nor night, who worship the beast and his image, and whosoever receiveth the mark of his name. (Revelation 14)
13 And the sea gave up the dead which were in it; and death and hell delivered up the dead which were in them: and they were judged every man according to their works.
14 And death and hell were cast into the lake of fire. This is the second death. (Revelation 20)
The intertextuality here is undeniable, and yet it would be very hard to claim that the passage in Mosiah 3 is simply plagiarizing Revelation. Far from it. The passages use the same phrases to underscore similar points.
See this paper for more classification and detail on intertextual connections. I definitely don't claim to understand every aspect of this feature of the Book of Mormon text, but I believe examples like these provide very strong evidence in favor of the divinity of the Book of Mormon.