Pupcake

I've just noticed that the dog food bags are not only divided into 'puppy' and 'adult' but further divided into various types of adult formula, including one for 'dogs 7 and up.' Are these actually legit divisions, or just a marketing scheme? I mean, I know the puppy food is legit, and I suspect that an older dog, maybe 9+, could use different nutrition, but 7? Last time I looked, 7 was still considered maturity, not seniority, for a dog of average size.