These additional blessing statements imitate but do not completely replicate the Old World form. This slight difference suggests that, when the Savior began his sermon to the Nephites, the blessing statements were part of the sermon but the particular literary form was not part of Nephite culture. Therefore, when Nephi made his record, the transitional statements imitated the blessing form but not the complete form because he did not understand it as a literary unit. Only part of it was imitated.
Of course, this observation does not mean that Jesus did not speak in such a way to the people. It simply recognizes that Nephi had no way to record a word-for-word sermon as Jesus gave it and wrote this record some time after the fact. All sermons in ancient texts must contain an element of authorial construction simply because there were no recording tools that could accurately reproduce continuous speech.