[PepperdineG]

>What is the point of eating something that is hard to process and digest and has no nutritional value for you

Wouldn't that make it dietary fiber then? What's functionally dietary fiber varies from species to species, but like with humans we eat things exactly like that for GI health. Birds of prey for instance eat casting (fur and feathers) which is functionally like dietary fiber for them where it would be unhealthy if you just gave them a steak without having them also eat the indigestible bits as they wouldn't be able to properly form and regurgitate pellets. Certain animals might not need something that functions like dietary fiber but for at least certain animals - like humans - eating certain indigestible things is important for good health.