I was rewatching The Incident Part II last night, and was struck by the Richard/UnLocke scene in front of the statue, right before Ben/UnLocke go in to kill Jacob. Richard says that only the Leader can request an audience with Jacob, and there can only be one Leader at a time. UnLocke's response? "Sometimes I think you made these rules up." And Richard acquieses.
We've heard a lot about "the Rules" on this show; some rules have been made explicit, some we've only inferred. But the only thing that seems constant is the fact that these rules KEEP GETTING BROKEN.
Richard says there can only be one Leader at a time. Well, what were Charles and Eloise? Ben says the person who turns the wheel can never return. Then Ben returns. Richard says that only the Leader can see Jacob---yet most of our Losties have, unknowingly, met Jacob. Ben (with Richard's apparent approval) exiles Charles Widmore because, among other things, Widmore kept leaving the Island. Yet we know now that Jacob himself keeps leaving the Island. Ben thinks Widmore can't order Alex's death---yet Keamey kills her.
When someone with supernatural ties tells you something, you do it. We've seen it with Locke/Christian, Richard/Left Behind Losties, etc., etc. So when a semi-immortal man tells you "The Rules", you take him at his word. After all, the guy never ages---he must know something we don't!
I think Richard invented "The Rules" in an attempt to reign in the various Leaders. He can't order them around (once he's turned over power) but he can manipulate them---bind them with rules so that they aren't corrupted by the near-limitless power of the Island.