There are dog treats for every age, every breed, every weight and every imaginable taste. However, not every treat is suitable for every dog and certainly not in every situation.
On the one hand, there are health reasons. As with humans, there are also allergy sufferers in dogs who cannot tolerate every ingredient. Nausea, vomiting, flatulence, bowel movements, stomach cramps and more are the result of careless food intake.
A certain amount of forethought or (more likely) consideration is also required with puppies: a puppy's stomach is still in the development and growth stage, so to a certain extent, which is why you cannot simply give a puppy the same treats - and certainly not in the same quantity - as an adult dog.
In addition, puppies need puppy milk, especially in the first four weeks of their lives.