That is not true. You could put a plant in pure water provid it with all the light and CO2 it neads and the plant will die. The reason is plant need nutrients dissolved in the water to grow. the nutrients are nitrogen, potassium, calcium, magneisum, phosphate, sulfur, chloride, iron, manganese, boron, zinc, copper, molybdenum, and nickel.
So you need all the nutrients available in the water plus light and CO2 to get growth. If you are missing any one nutrient, CO2, or light you get no growth. if all are pressent but scarce you will get slow growth. If all are available in unlimited quantities you will get rapid growth. it is quite common for plants to grow slowly in aquariums because one nutrient is scarce or becauseCO2 is scarce. light is often not scarce because we can see it. but you cannot see CO2 or dissolved nutrients.
Another common problem is that apeople buy a fertilizer thinking it will provide all the dissolved nutrients plants need. But the sad troths that most don't have all the nutrients needed or have nutrients or will have nutrients that onlywork at a specific PH, or KH range. Unfortunately none of this is ever mentioned on the bottle.