A team forms in order to complete a project.  The "leader" doesn't really do anything to help define success criteria, identify the general approach they'll take, or contribute to resolving detailed issues.  Eventually someone else on the team steps up and fills in the gap.

Was this an example of self-organisation? Yes.  It's also an example of an incompetent, absentee leader that the team was able to compensate for by identifying an actual leader.
A team forms in order to complete a project.  The leader independently defines the success criteria, independently identifies the general approach to be taken, and is involved in resolving every detailed issue.  The "team" simply does what the leader tells them to do.
Was this an example of self-organisation? No.  But it is an example of an incompetent, authoritarian leader.
So how can you tell the difference between someone developing the team to be more autonomous versus someone who is just incompetent?
If we remove the leader and there is no loss, that probably means the leader was useless.  If we remove the leader and there is complete and utter collapse, that probably means the leader was incompetent.  If we remove the leader, and there is loss but the team compensates and continues to improve, that probably means the leader was useful and competent.