He then follows with a series of criticisms of the text as well as Joseph Smith. Among other things, the author criticizes the 3 Witnesses. "But if the plates were hid by the angel so that they have not been seen since, how do these witnesses know that when Smith translated out of a hat, with a peep-stone, that the contents of the plates were repeated and written down?" (p. 78)
When viewed in this context, we can better understand why Oliver Cowdery wrote about Cumorah the way he did. He said it was a fact that the final battles took place there. He said Mormon's depository was in the same hill. He explained that "thousands" of Jaredites died there, and "tens of thousands" of Nephites and Lamanites.
In short, Oliver wrote Letter VII to establish facts that contradict the messages of anti-Mormons as early as 1844. In our day, we also need to be familiar with Letter VII and the other historical letters for basically the same reasons.