... Think about it like this sheep. If you have a leader, you are organized. Once he dies, there is anarchy before things settle back down to normal. In a scenario with no leader, then there is no death of the leader and thus no reason to go into a panicked anarchy.
+K, I find it funny how some people love the lightkeeper but hate the leader, considering the fact that the lightkeeper is a crappier version of the leader.