I can't agree, because there are ingredients in hair products as well as in internal aids (like vitamins, supplements) (i.e. biotin) that are proven to make the hair and nails grow at a faster rate. It is true that the vast majority of products out there have no effect on hair growth rate, but instead aid in retention.
However, there are chemicals and natural substances that do enhance growth. Because of this, many companies put them in hair products. (Here are a few: sulfur, inositol, pantothenic acid, biotin, vitamin D, vitamin A, B vitamins, etc.). And the list goes on...
Just because she believes no product makes the hair grow, doesn't mean it's true. I'm sure she's no scientist or chemist, and is just making a generalized statement based on her own results. I, for one, can attest to certain products enhancing my growth rate. I took the time to do an experiment to rule out other factors (i.e. vitamins, diet, supplements, etc). And, I also took the time to research the ingredients in the product(s) to see which ones have a scientific/medicinal property of increasing growth or decreasing hair loss. That is how you separate fact from fiction, from opinion. Topicals CAN increase growth rate.