Ok this was mentioned by Mayuri around the beginning of the story arc, the balance of souls, now we all know there is a constant balance between the Human World, Soul Society and Hueco Mundo. Now when the hollows were being killed off by the VR Mayuri took steps to restore the balance temporarily by killing off several Rukongai citizens, in the aftermath of the First Battle of Soul Society there were over a thousand confirmed Shinigami deaths, the number could be even significantly higher but there is no way to know for sure, so my question is between the death of all these hollows, the Rukongai citizens and the Shinigami wouldn't throw the balance off quite a bit and having too many souls being reincarnated to the human world? If that is the case would that mean that they have to kill off several humans to balance everything back out, and if so that is bound to be very much noticed.