Eat more fiber? Only plants have fiber.
Eat less saturated fat? There are only a handful of exotic plants that have palatable saturated fats, palm, palm kernel and coconut. Otherwise, it’s only in animal products.
Eat less cholesterol? Only animal products have cholesterol. The body can regulate it’s own cholesterol.
Too much iron? Only animal products have heme iron which the body can’t regulate.
Hormonal imbalances? Only animal products have hormones similar enough to our own to disrupt our endocrine system.
Eat more fruits and vegetables? At only 100 calories per lb, these are displacing many animal products, but they sure aren’t made of animals.
I think science is just picking up on all the qualities of animal products, but the researchers, either addicted to meat and gluttons for more are unable to bring themselves to a conclusion that the optimal amount of animal products in the diet is zero.