I'd like to ask a more specific question than my sibling's excellent "Wait, why?" question :)

Why offer erasers on these things? The procedure described below has nothing to do with using these as pencils, and at $500 for a pack I can't imagine anyone, anywhere casually drawing with these.

(Is there another procedure, similar to the one described below, except instead of dragging the pencil tip across a surface you drag the eraser across it? )