I've always fed my Rottie puppies all life stages food as opposed to puppy food and kept them on what the breeder was feeding. However, I can't say that never caused problems. In one case the breeder had just switched to something she'd never used before, which I didn't learn till later. That puppy did develop panosteitis, but fortunately not a bad case. It went through each leg and disappeared. When I investigated, that food had a high calcium/phosphorus ratio, which is suspected to predispose to pano.
With one of my other puppies, she always seemed like a poor eater, not finishing meals, sometimes not eating at all. Very un-Rottweiler-like and frustrating. Since she's also a softer dog than any of my others I thought it went with the territory so to speak, but when I finally switched her off that food, she never again didn't clean her dish with enthusiasm.
So while I'd always keep a new puppy on what the breeder was feeding for a while, I'd no longer be inclined to continue feeding that food without some research, and if the puppy wasn't enthusiastic about it, I'd at least switch once to make sure it was the puppy and not the particular food.