If you, as a grower, do everything right - light levels, duration, and periodicity, temperatures and temperature variation, humidity, air movement around the plant and its root system, nutrition and watering - you allow the plant to grow and bloom to it's maximum potential. There is nothing you can do that overrides genetics in that respect. On the other hand, any cultural shortfalls can, and likely will hinder the plant from reaching its potential.

So when you hear someone describe, or read an ad for something that's supposed to "make your plants grow better", you have to evaluate whether or not it is something that will improve your culture by eliminating or reducing a shortcoming and therefore allow your plants to do better, because you're simply not forcing anything.

One might argue that rooting hormones might be categorized as growth enhancers, but they might also be considered as "shortfall removers", as while they do stimulate the growth of new roots, there is no evidence that it is of any advantage, except in the case where they root system was deficient in the first place.  In fact, repeated, excessive use of rooting hormones has been shown to be detrimental to plant growth and blooming in some cases.