One of the buzz words in many peoples vocabulary is "collaboration". We must be seen to be collaborative. We must act in a collaborative fashion. We must achieve our goal through collaboration.
Sometimes, not always, but sometimes collaboration is used as an excuse not to make a decision. There are times when collaboration is a good thing and there are times when a dictator is required. Don't misunderstand me, a dictator can be more than a Project Manager, it can be a process or policy that is created. They dictate your actions towards achieving your goal, the goal that was created in a collaborative fashion. However, a project is not a collaborative group of individuals striving to achieve a common goal. It's a project team.
If you are trying to solve something than collaborating with someone to come up with a solution is a good thing. However, the implementation of the solution is not necessarily a "collaborative" adventure. Collaboration comes in the act of creation, in the act of coming up with a solution for a problem. Do project team members collaborate? Yes, amongst each other.
Let's go with an example. Being in the IT field there are a lot of things where I need to collaborate with other people. Let's say that I want to implement a new standard for SQL Server. I will collaborate with the DBAs in my group, affected project teams, subject matter experts, etc., and come up with the standard. The implementation of that standard is not something which is a collaborative process. The collaboration occurred during the creation, not the implementation of the SQL Server standards.
Collaborate when you don't know the solution. Manage when you know the solution and you need to get there.