Good and skillful leader will help the team to maintain its focus on the main issues. A good leader encourages communication to make sure all possible opinions and solutions are being heard. The leader should avoid advices but then lead the team from problem identification to a plan of action.
Whilst the team should have a formal leader, leadership functions should shift from time to time depending on the circumstances, the needs of the team and the skills and qualities of the members. The formal leader models the appropriate behavior and helps establish positive norms.
If the same practices improves perfection, then why a need to shift leadership functions from time to time. What about if most of the team members do not have leadership skills. What would you expect from your members as a team leader? What will you do as a team leader if your team members are not pulling their weight?