Social: These two verses are an accurate description of the underlying social organization of Mesoamerican cultures. Kinship was extremely important, and dictated any number of functions and associations. As Michael Coe notes:
“The ancient Maya realm was no theocracy or primitive democracy, but a class society with strong political power in the hands of an hereditary elite...
Now, while among many more primitive people such kin groups are theoretically equal, among the Maya this was not so, and both kinds of lineage [dominant patriarchal, and marriage-related matriarchal] were strictly ranked; to be able to trace one’s genealogy in both lines to an ancient ancestry was an important matter, for there were strongly marked classes.” (Michael D. Coe. The Maya. Thames and Hudson. 1999, p. 196).
Coe is describing the conditions of a time later than the Nephites, and the system that supported the kingship system among the Maya. Its relevance for our current discussion is that it is simply the continuation and extension of these same factors as we are seeing in Nephite society. Of course the class rankings of the lineage is the heresy that the Nephite gospel was combating, but the underlying social organization certainly existed.
When the political order than held the clans together was dissolved, the people remained, but automatically fell back into the clan organization, which is here described as tribes. The continued importance of the kin groups even inside the larger political organization is confirmed by Mormon’s comment that “there was no man among them save he had much family and many kindreds and friends.”