In the video showing the cavitation comparison, why aren't the central parts of the propellers more hydrodynamic? Like the typical pointy shape. It seems like i

In the video showing the cavitation comparison, why aren't the central parts of the propellers more hydrodynamic? Like the typical pointy shape. It seems like it would make the contrast between the two propeller designs at the blade tips more apparent if the predominant source of cavitation wasn't due to the feature they have in common.