Communications were much more difficult in the ancient world, and it is not surprising that Chief Captain Moroni only learns of the problems in the land of Morianton by those who left that land and presented their case. There are a few instructive historical lessons in this event.
The first is that this is a fairly new community. It was named for their founder (see verse 28), who lived among them. This confirms that the newness of the settlement was one of the reasons for the dispute with the city of Lehi mentioned in the previous verses.
Second, when Morianton decides to flee because he fears that Moroni’s army will come against them, he does not go south to the Lamanites, but he attempts to go north. At this point in the Book of Mormon, we have seen little of the land northward, and know only that it is a land of desolation. What we learn here is that it is also somehow dangerous, and heading in that direction “would have been a cause to have been lamented” (verse 30). There must have been people there at that time, and Mormon implies that those in the lands northward could be dangerous. That is a theme that Mormon will continue to develop.