I have a basil plant that is approximately doubling in size every day while in standing water, and was wondering why people say not to overwater basil?
Many plants grow fine in water. That's the basis for hydroponics. The main methods are deep water culture, flood and drain, and thin film. They all have in common moving water to ensure that the dissolved oxygen levels remain high enough so that the area around the roots doesn't become anoxic. If they do, the roots suffocate, die, and rot.
If your basil plant is doing well in muddy water, then you must have enough surface area to allow sufficient oxygenation for the plant to survive. Basil is commonly grown hydroponically so it's a good choice to try this out. But muddy water is not a sufficiently controlled environment for commercial growers. It may or may not have enough nutrients for the plant, and growers want to control all the variables to get the best growth.
Just found that there are no answers here so here goes. Growing stuff in water is just fine, if there is enough light, ventilation and proper amounts of chemicals/fertilizers. One basil plant no big deal. But most gardeners like to use the NORMAL way to grow plants that are not water plants in soil that is available all around us. When one over waters in SOIL, like Bamboo explained, you've got the perfect conditions for ROOT ROT (and other fungal, bacterial conditions).
Growth better maybe, but if you are not selling things per weight, possibly it is not the better solution
Many vegetables gives much more savour when there is some stress on plants.
When doing home gardening, one should not check about quantities: we will never compete with wholesale (with prices), but we can produce much more tasty vegetables (which wholesale cannot really do, if not much pricey).