It's not just about moving the stuff up, it's the larger surface area to gather the stuff in. A central screw can't pull stuff toward it. This is the same problem chopping ice in a blender. Once the (dry) stuff around the spinning part is shredded, it's less likely to churn additional material. The external tube is simply directing significantly more product to the blade than a moving blade can pull. Plus the blade isn't moving to whip the product like merengue. The product is simply moving up because more product is pushing up from the bottom. I am curious if this has any liquid/ height restrictions or is it limited to dry/particulate products. Imagine turning this on its side for propulsion in the water.