As fighting becomes widespread “upon all the face of the land,” the organizational unit was the clan: “every man with his band.” Even through Ether’s obsessively dynastic focus, it has been apparent that clans controlled the government. This detail confirms it, with the added development that the larger political structures have been so disrupted that kin-groups have become the basic governmental unit. The model continues throughout Mesoamerican history, including Nephite history, even to the reversion to government by clans (3 Ne. 7:2). I believe that Moroni saw this development as directly parallel to the Nephite “destruction” that preceded the appearance of the Messiah in Bountiful.
Ether does not specify what the clans “desired” that motivated their fighting. Most likely, they were defending their ancestral lands (or acquiring more) and assuring control over its resources.
Ether 13:26
26 And there were robbers, and in fine, all manner of wickedness upon all the face of the land.
Redaction: The mention of “robbers, and… wickedness” is Moroni’s perspective. Certainly he understood his father’s view that Gadianton robbers had toppled the Nephites into destruction, both before the Savior’s visit and in the final destruction. By “robbers,” Moroni means representatives of the secret combinations, not ordinary thieves and brigands. Moroni is patterning the Jaredite destruction on that of Nephites, blaming both on secret combinations, or the “[Gadianton] robbers.” This language following the Jaredite dissolution into clans is an important literary parallel to the Nephite dissolution into clans that was associated with the Gadianton robbers in 3 Nephi 7:2.