No one can bypass the essentials of food, clothing, shelter, and transportation. Holding such a thing in hand, everyone feels at ease. However, the current Northern aristocratic families who hold the wool can't promote it for universal use because the sheep wool isn't enough!
Is this a reason? Of course it is. The Hu people on the Great Prairie only have so many sheep, while the Central Plains have so many people. It's no wonder that the wool production from two to three million sheep is not constant. This is why later on, aristocratic families angrily scolded the Hu people for not being able to raise sheep, demanding they cede the grasslands so they could raise sheep themselves!
Thus, although the Northern Grasslands hasn't been conquered yet, what was previously thought to have no output and no significance now has a large group of aristocratic families marking them for sheep raising, wool production, and eating mutton.
