Comparing Individual Ingredients in Pet Food vs Comparing the Whole Diet

I realized that perhaps we disagree on pet food because there's really two camps. There's the folks that focus on comparing individual ingredients, deciding one is good and one is bad, or one is appropriate and one is not, or one is high quality while the other is low quality. And that could be accurate if just comparing individual ingredients. But the other camp, which I am part of, compares the combination of ingredients in a complete diet. Sometimes, there's a specific reason for an individual ingredient to be included in a diet for a specific purpose.