My grandmother used to piece quilt tops from scraps she received for free from a hat factory in the area. She didn't realize that the fabric was very poorly made. It did not hold up well at all, and soon began wearing through. These were not heavily used/washed, either. Just the poorest quality fabric, probably not even available for consumers. In the factory, I think it was bonded to a stiffer backing, for the hat construction. She just used it because it was free. A pity, all that work didn't last.
My point is, some old quilts are not worth saving. And, I appreciate good fabric even more now.