Because they're missing out on the nutrients present in meat.
Meat contains nutrients such as protein.
There are tens of different combinations (at least), for risotto ingredients. You'd have to be more specific. Is its broth meat-based? Are there vegetables or cheese present? Etc.
Carnitine and D3 and
find out what different nutrients ?
protiens
protiens
fats
carbohydrate
portein and iron
Minerals and vitamins
main one is protein