All that I've learned about Bane, shows me that he and his "Rule of Two" are PERFECT embodiments of what the Sith are all about.
The Force is a Sith's Power. The more Sith there are, the less power each single one has.
Bane even said it best himself: "The Force is not Fire. It is Venom."
The Darkside is at its strongest, most potent and downright deadliest when focused and NOT shared among others.