Diamond naturals chicken & rice is not grain free; rice is a grain.
I have nothing against this food; we buy the Costco branded version of it (120-160lbs at a time).
I too agree the grain free diet fad is pure marketing. They are selling “feed your dog what a wolf would eat in the wild”. But then then tell you this fairytale of what wolves eat in the wild. They leave out the facts of wolves eating organ meat (meat byproducts) first then muscle and finally bone (meat byproducts); and wolves eating vegetation (grass) in the summer. Almost forgot to mention the consumption of rodents, birds, and invertebrates (more meat byproducts like feathers).
Source: https://academic.oup.com/jn/article/136/7/1923S/4664711
But why let the facts get in the way of a good story.