One of the principles of Agile Project Management is
Group accountability for results and shared responsibility for team effectiveness
The shared responsibility for team effectiveness idea is powerful in that it removes the blame game from play. The methods of implementing this shared responsibility vary but one is to establish a Group Norm for behavior and develop a support network to install this behavior. This is the Al-Anon approach.
The Group Accountability is a bit more problematic. What I've observed in the group accountability mode is that decisions don't stick. Consensus only is not sufficient, concurrence is necessary. What this means is when a decision is made no one in the group can make another decision - the decision sticks, period. The result is a single point of integrative responsibility acting "as if" it were a single person, not a group.
So if the group is accountable how does the group come to a place where decisions stick? This is one of those differences between principle and practice that is missing from the Agile PM discussion to date.