Your plant growth will be limited to the level of its most unavailable resource. If Co2 and fertz are good, but there is no light to match and keep up with the capacity provided by Co2 and fertz, then growth won't be at it's potential. If you then increased light to match the requirements/capacity provided by the Co2 and fertz, you would see growth increase until it's reached terminal growth for the resources provided.
A lack in nutrients, co2 or light will inhibit growth, so swap out any part of the equation for another part and you get the same result. (Good light + good fertz + poor Co2 = sub optimal growth, etc, etc, etc...)
So if you don't currently use any Co2, just be sure to dose appropriately and I'm sure things will take off!
That's how I've always wrapped my head around it. The "growth chain" is only as strong as it's weakest link. Haha.
Lo, they do call to me.
They bid me take my place among them
In the halls of Valhalla
Where the brave may live forever.