
Many reasons, I’ll put one simply (also, stupid ≠ uninformed don’t put yourself down): Flora, like trees, need water to live. Usually the rain cycle doesn’t take too long to provide the trees with what they need. When something artificial uses a vast amount of water all of a sudden, even when the water will eventually come back, the flora loses out on some of the nutrients that they need. Little by little, the flora is starved.