Diamond engraving cutters

Hi,

While we're on small cutters, could someone tell me why we SPIN a
diamond at high speed (Dremel) to engrave? I looked at the $15 Dremel
diamond and carbide "points" I just received, and the diamond looks like
it just comes to a point. I think the carbide has a flat on it to cut
with.

HT09029240
CARBIDE POINT FOR
DREMEL ELECTRIC
ENGRAVER
4.99

HT09029299
DIAMOND POINT FOR
DREMEL ELECTRIC
ENGRAVER
14.99

Alan KM6VV