Did teasing fabric come before teasing each other? Or vice versa. Either way, you can picture why one becomes the other.
Anyway, I've wondered about using these to raise nap on fabric. Seems like they would leave behind some very uncomfortable debris. But they are still sometimes used rather than the modern metal cards designed for that. Teasels are more gentle to the fabric. A sharper mind must have come up with a way to get rid of the broken spines.