Just to reinforce @pastrygirl's point about tradition
"Marcella Hazan changed how we cook and experience Italian food. A disabled woman trained as a scientist, Marcella never cooked until she immigrated to America. But through her cookbooks and teaching -- and an uncompromising commitment to Italian tradition -- her impact was felt in millions of American home kitchen."
Ghee is an Indian tradition. Why doesn't she make spaghetti curry?
Butter is a relatively unused ingredient in Italian cuisine, its use being confined mainly to the north, where this dish presumably originated.
