Because once you use this method, it's like killing the chicken to get the eggs, and this killing is fatal, even though it can briefly improve everyone's strength.
However, the consequence will be a lack of successors.
In such a situation, if any unforeseen change occurs and the high-level high combat power results in death, the low combat power will not be able to support, leading the entire cultivation world to fall into decline, even if the Power of Heaven and Earth intervenes later, it still won't recover in a short time.
But if that urgent situation truly arises, then, for its own sake, the Power of Heaven and Earth will use this method because if it employs this method, the inner realm will rapidly return to its most prosperous era.
Yet this prosperity only pertains to the present era; it cannot be maintained thereafter, because all the qi has been used up by those currently living.
