Multiple sources have put forward this argument.
For example, the Journal of Book of Mormon Studies article Stylometric Analyses of the Book of Mormon: A Short History (link) affirms:
The abundance of skeptical theories about who wrote the Book of Mormon has led many scholars to seek scientific data to discover the answer. One technique is stylometry. Having first been developed in the 1850s, stylometry seeks to find the “wordprint” of a text. Although these stylistic studies are not as accurate as a human’s fingerprint, they can give researchers a good idea either of differences in style between authors or of who might have written a text from a list of possible authors. Beginning in the 1960s individuals have completed four major stylometric studies on the Book of Mormon, studies that varied in both findings and quality of research. In addition to these four studies, this article presents a fifth study—using extended nearest shrunken centroid (ENSC) classification—that incorporates and improves on the earlier research
Stylometric analyses of the Book of Mormon have generated much interest over the past thirty years. Some of these analyses have produced interesting information, but some of the studies have been characterized by hyperbole, faulty reasoning, and misapplication of statistical methods. When examining all the evidence, our overall conclusion is that the Book of Mormon displays multiple writing styles throughout the text consistent with the book’s claim of multiple authors and that the evidence does not show the writing styles of alleged nineteenth century authors to be similar to those in the Book of Mormon. Further, the claims thus far put forward for alternative authorship of the Book of Mormon, other than as described by Joseph Smith, are untenable.
Similarly, the article Is Stylometry the Ultimate Proof that Joseph Smith Did Not Write the Book of Mormon? (link) states:
[...] Together this presentation helped the audience consider the impossibility of someone of Joseph Smith’s age and limited experience working with Oliver Cowdery over 60 working days to compose anything so complicated as the Book of Mormon. It worked for me and others in the audience.
[...] Like Fields and Roper, many other scholars have used stylometry to show the distinctive styles of the book. These studies show that the major contributors, Nephi, Mormon, Moroni and Alma, all have distinctive “wordprints” in comparison to Joseph Smith’s. Clearly, he did not author the book, but a team of many writers compiled it and none of them were Joseph’s contemporaries.
User @HoldToTheRod presents the stylometry argument too in his answer to the question According to Latter-day Saints, what are the strongest apologetic arguments for the divine inspiration of the Book of Mormon? :
- Positive arguments
In order to pretend to be concise I'll just focus on 3.
(Drawn from Book of Mormon Authorship – New Light on Ancient Origins)
Stylometry studies word-prints and offers a means of determining who wrote an anonymous text. Like a fingerprint, people leave traceable patterns in their writing. Very small samples (e.g. a few verses) are insufficient for statistically-significant stylometric analysis, but longer passages are quite relevant and the scientific apparatus is well-studied. Stylometry has been used to determine authorship of a variety of documents, including some of the Federalist Papers.
An author’s word-print has been shown to survive translation, and authors who try to game the system and mimic another author’s style have been betrayed by their own unconscious writing habits—stylometry can catch the ruse. Even when an author has multiple characters who speak and behave differently, the author’s word-print can be discerned.
The Book of Mormon has been subjected to stylometric analysis which has demonstrated, among other things:
- Neither Joseph Smith, Oliver Cowdery, Sidney Rigdon, nor Solomon Spaulding wrote the Book of Mormon
- The Book of Mormon was written by multiple people. I.e. Nephi, Alma, Mormon, Moroni etc. are not just different characters—their words were written by different people
The authors of the aforementioned Book of Mormon Authorship provide an extensive discussion of the statistical data, and they offer rebuttals to counterarguments that have failed to capture the depth of the stylometric analysis that has been performed.
How do non-LDS Christians respond to the stylometry argument for the authenticity of the Book of Mormon?
- Between the Bible and the Book of Mormon, which one has a more plausible alternate account of its invention?
- What are scholarly objections to the divine inspiration of the Book of Mormon?
- Why do non-LDS Christians accept the testimonies of the apostles but reject the testimonies of the 3 & 8 witnesses to the golden plates?
- According to Latter-day Saints, what are the strongest arguments for the credibility of the 3 & 8 witnesses to the golden plates?
- According to Latter-day Saints, what are the strongest apologetic arguments for the divine inspiration of the Book of Mormon?