What a retarded question!
There are recipes that use penne.
Furthermore it's retarded because it can apply to hundreds of items.
Eg: How come chili doesn't have fish in it?
Eg: How come potato salad doesn't have fish, beef, beans, or corn in it?
Eg: How come eggs aren't a pizza topping?
And it's usually a side dish, genius - meaning it can be on a plate with a steak, veggies, or whatever else someone wants, in the same way backed potatoes and rice and pasta are side dishes.