Ever see a cookie dough cutter make shaped cookies? You can eat the extra dough left over, but not so much in fashion. Fabric also comes in massive rolls and deadstock materials are the "left overs," whether from cutting out shapes to sew into garments, or if the fabric was the wrong color, or many other reasons. Using deadstock materials means not using resources to make new "virgin" materials and it means keeping fabric out of landfills. We're dead rn.