I'm not a groomer, only the husband of a groomer. As I understand it, the coat may not grow back the same.

A poodle puppy coat is very soft and wispy. The adult coat is thicker and curlier. You may be able to maintain the puppy coat longer by not grooming your puppy. That may be why some people recommend against it?

But poodles are not double-coated. On a double-coated dog, shaving the coat can cause damage. That's not the case with poodles. Poodles will not be harmed by being groomed, and they should be groomed young so that they get comfortable with it, because it's going to be a regular occurrence that they'll have to live with for the rest of their lives.