[gouranga]

It doesn't as not all movements are as accurate with your fingers.

Pushing down and aligning your fingers is incredibly accurate but rolling/moving your fingers is not.

[Lewton]

Hm, you might be right. But as how I understood it, the datahand is trying to let you use the same movements as you are already using on a normal keyboard, only without having to travel the full distance. I have a hard time seeing why that shouldn't work

[gouranga]

Try typing with your nails down on the keys i.e. with curled up hands and you will see.