Accountability is the ability to take responsibility for a specific task.
It is essential in a self-organized environment.
Indeed, in a self-organized workplace, trust and transparency are essential because they allow everyone to focus on their roles and missions, safe in the knowledge that everyone else is doing the same and that everything the organization needs to move forward is being taken care of by the appropriate individuals.
Be it at individual, team or organizational level, without accountability, you can't have trust and transparency.
And without trust and transparency, individuals, teams and organizations cannot successfully implement self-organization.
Indeed, if you don't know what others are working on or don't trust that they're doing a good job, self-organization can't work.