"The force is not fire. It cannot be passed from one user's lit torch to another's and another's." (Darth Bane, Book of the Sith.) Darth Bane stated that the force is venom and if you share it, it gets weaker and weaker and weaker. So The Rule Of Two states that the master has to have all the power and when the apprentice kills him/her, he/she should pass on the power.
Pretty simple if you ask me!
Also, he states he likes to kill Jedi.