I don't think it is common sense at all. The trade goods nomadic herders "carried" with them were their flocks. Which weren't carried at at all, but walked on their own four feet.
Carrying other stuff would have made tending the flocks very difficult.
Gold and silver are the marks of a trader who has traded with other traders.
A good obsidian salesman would actually hunt up the nomads to peddle his wares.
That’s what salesmen do
Nomad daughters anxiously awaited the coming of the salesmen
***********
A traveling salesman is in Nineveh when he comes upon a house with a little boy sitting on the front steps.
“Son, is your mother home?” The little boy nods yes.
“Can I see her please?” The boy nods again, and they go around to the back of the house where they find the mother on the ground, humping away with a sheep.
“Son, do you see what your mother is doing?” The boy nods yes.
“Do you know what that is?” The boy nods.
“Doesn’t that bother you?”
“Naaaaaaaaaaaah!”