No-one has said that preservatives and additives are good for dogs.
Personally, I choose to avoid preservatives in my diet, and in the diet of my family and my animals.
However, as stated, domestic dogs have evolved over the last 30 thousand years and the nutritional needs of a dog that lives on a lounge, in a house, and goes for a walk once a day is not the same as a wild animal, that is on another twig of the tree, that may travel kilometres in a single day looking for food.
Wild dogs do not even eat daily. Are you going to feed your dogs every other day instead of twice a day?
A wild dog digests raw meat easily. Many domestic dogs can not digest raw meat and find it too rich.
As for studies, everyone these days is a google expert. I am sure you can also google. I don't have the desire to 'prove my comments' on this forum by regurgitating studies found on the www.
Looking at domestic dogs in SE Asia in particular shows that dogs do not need meat to survive. There many dogs in many areas that survive on a diet of coconut husks and scraps. Do they live long lives, I doubt it, but they manage to have litters and continue to survive.
The simple fact of it is, a dog will survive on commercial food, kibble, vegetables, a raw diet, a prey diet or barf. Feed your dogs on what you feel is best, but remember that it shouldn't be as hard as what many dog owners now want to make it. Dogs have lived to ripe old ages after being fed PAL all their lives, and equally there are those who have lived to ripe old ages being fed raw, barf or something else.
As they say - the best food for your dog is the food it does best on. Don't get caught up in the hype of dog diets and don't let anyone guilt trip you into changing to something else.