Why Are There so Many Doomsday Systems?

[Zombie apocalypse + extensive system + shared system + farming story + heroine's decisive killing] Chen Mo is an ordinary social animal. One day, when he was taking the bus to work, a zombie virus suddenly broke out in the city. After escaping into the hotel where the reborn person was, he heard an electronic sound next to his ear: "Ding - Congratulations to the host, binding the farm and material system!" Just when he was complacent, things turned out not to be what he thought. No, what is going on? Who can tell me why there are so many systems! Why are my wife and I connected to the same system?