Probably for a worst case. The lignite carbon is generally softer, allowing it to break down easier, introducing more dust (and it starts with a good bit of dust). While the extruded comes with its share of dust, it holds it's shape longer (not breakign down as easily). In large aquariums, they are likely using large amounts of carbon, so skipping a step (or rushing a step) here and there is probably more likely(?). May be more real world for some situations. Even with some rinsing, large quantities may still introduce relatively large amounts of dust (harder to rinse large quantities at one time than smaller qtys). It also proves their hypothesis, so it adds a little depth to the experiment. Just thinking out loud (never worked for a large aquarium). For me, the benefits far outweigh the detriment, so I will continue to use it. The study serves as a cautionary, though.