Jerry, to a point I agree with you. The advertising promotes things that are palatable to people on the one hand while dismissing ingredients that might be objectionable to a person's sensibilities. That isn't necessarily what a dog or cat needs for a complete and nutritious diet.
What I don't agree with is that you can easily cook and or prepare a meal that is nutritionally complete for your dog or cat. Their needs are NOT the same as people.
Most reputable larger pet food manufacturers utilize veterinary nutritionists and routinely test their diets on a multitude of breeds and species.
For all of you, in your travels if you ever have a chance, take a tour of the Purina Farms in Gray Summit, Missouri (just outside St. Louis). It's an interesting tour and shows the research behind a major animal food manufacturer.
I have less faith in the boutique pet food manufacturers. There are so many now and it's difficult to know if they really have done the work to provide a nutritionally complete diet.
Bottom line for me, it's way easier to provide a nutritionally complete diet staying with a major brand of dog or cat food than preparing one yourself. Another "rule" for me is there is no one food that is best for every animal. What may be great for one may not be best for another.
Doug, DVM