3 Nephi 4:18

But behold this was an advantage unto the Nephites; for it was impossible for the robbers to lay siege sufficiently long to have any effect upon the Nephites, because of their much provision which they had laid up in store

But this helped the Nephites. The robbers could not surround them long enough to hurt them. The Nephites had stored up too much food.

But this actually worked in the Nephites’ favor. The robbers couldn’t maintain a siege long enough to matter, because the Nephites had huge stockpiles of supplies.