I think that a lot of the food that we buy in the store to eat that is sold as being healthy, is actually over processed, and has lost most of the vitamins and healthy enzymes that are meant to be in our food, so it is not just the dog food that is not healthy, it is pretty much a lot of the commercial food products.
Now that they are using the genetically modified seeds to grow crops, things are becoming even worse, and many countries are forbidding the use of the GMO seeds.
Even though I make food for my dogs, I still put out some dry dog food for them, so they have something to crunch on, and it is supposed to have extra vitamins supplemented in it.
Short of living on a farm, and raising all our food ourselves, there is really no way to avoid consuming some of the commercial foods made both for us and our pets.