How sharp should a device be?
Imagine trying to use a pencil to poke a hole in an orange. You try to push it in but it is very difficult to break the skin of the orange. Then the pencil tip breaks and the orange is mangled.
Now imagine that instead of an orange it is a patient in the operating room. And instead of a pencil the surgeon is holding a medical instrument, which she is going to use to perform a delicate procedure on the patient. You would not want the situation to be like that of the pencil and the orange!