When we are involved in a group, doing something that tapers toward a good end, an expected result, it is important that we don't act passively.
It is required in team work that every member of the team contributes towards the success of the project.
A team is as strong as its weakest link. It's like the one Jonah that brings great loss to the ship.
Two heads are better than one seems okay. However, it's two good heads that are better than one. Any other thing is the recipe for disaster.
Victory is sweeter when everyone is involved. Otherwise, one is happy, another doesn't value the victory because he didn't sacrifice enough.