the way I look at it, is that dogs survived for millions of years, long before even human beings were on the planet, killing and eating other animals. they ate the offal, the flesh, the skin, smaller/softer bones and the contents of their digestive tracts (vegetable matter, grass etc). watching lions, hyenas & wolves today in the wild you see the same things happening. Their bodies are designed to digest and use fresh raw meat. Dry kibbled/biscuit foods only really came into the picture in the last century, when people needed to save as much quality food and meat for themselves and the dogs were fed sweepings and cheap filler grains instead. Dogs were once fed primarily on butchers off cuts and carcasses but during the wars nothing could go to waste so cheap kibbles became popular.
It makes sense to feed naturally.
when I got my bitch at 16 weeks old she'd been fed on Wagg puppy food. her coat was dull and what came out of her was yellow, soft and stunk. I switched her onto a slightly better quality feed but nothing changed. tried Burgess greyhound&lurcher, her waste became grey but still lose. tried James Wellbeloved and there was some improvement but it was very expensive, also tried a 2kg sample bag of something from the vets that was very high meat content (can't remember the name but the kibbles were soft and meaty) - she liked that but would have been even more expensive and she was still having the runs sometimes.
A friend of mine then mentioned raw feeding so I started getting minced rabbit or chicken from the Prize Choice range, and have never looked back. mix it with a bit of veggies and some rice or porridge oats or something, and her coat began to shine, she became more well muscled, and what came out the other end was just how it should look. I give regular raw beef ribs, lambs legs and the odd chicken wing for diversity and she's in cracking condition. no more flaky skin too! she eats the occasional rabbit that she catches too, which is as natural as things get. the only processed food she gets are gravy bones - as the occasional treat