Stockless anchors fit better up against the side of a hull
at the end of the hawse pipe. Weight is not as much of a concern either with ships as it is with recreational boats. Additionally, the weight reduces the chances of the anchor jamming up inside the hawse pipe. An anchor with little weight and a large surface area would be a nuisance in heavy seas as the ship pitches into the swell and the seas hit the anchor causing it to move slightly.
Given their weight per amount of surface area (holding power), they are not one of the better designs for recreational boats but are fine for ships with hawse pipes.