A decade ago, my company started a new division using a self-directing team: No boss. Within a few years they had returned to the traditional supervisory model; the experiment was a bust. The power vacuum prompted a power struggle between a couple of forceful people, and the team split into factions.
Self-directing teams can be effective if organized well and used appropriately. Often they fail, and usually because someone bought into the fallacy that self-directing teams don't need leaders.
Immutable law of the universe: Every group needs and will find a leader. Just watch kids on the playground, or your employees after you announce you can't give bonuses this year. Any time a group of people acts together, it's because someone got them to agree on what to do. Without leadership, people act as individuals.
This is true even when no leader has been appointed. Any time a group forms around a common cause, a leader will emerge. Someone either takes charge through a dominant personality or is given leadership because he or she has a lot of influence. But the group wants to be led; most people want to do, not decide.
Even a self-directing team needs to be told on an operational level what to work on, to have its boundaries set, to have regular input and guidance to keep it on the right course, and to have accountability. The occasional tie will need to be broken. Those parts of leadership must be external to the team.
Teams can effectively self-direct in choosing how to do work, when to do it, and to some extent what to work on. Self-directing teams can be very effective problem solvers and improvement finders; they are inherently more creative than directed teams. But even in doing those things, you will observe that someone will step up and lead, enabling the others to cooperate and get things done.
Use self-directing teams in situations where they and the organization will benefit. Just don't succumb to the fallacy that there is no boss. It's either you, someone you designate, or someone that emerges, but they will have a leader.