When a team communicates they are able to work together. Each person takes on the roles that they are strongest at while having the others help them on the weaker points. Without communication everyone is left working on their own, possibly overlapping and surely struggling on the areas that aren't within their expertise.
Sharing The Workload
It isn't possible for one person to do the work of a whole team. Good communication allows team members to ask for help when they need it. Should someone find that their part of the project needs something that they can't provide, all they need to do is communicate. A failure to communicate in a need to share the workload can lead to a project being delayed and team members feeling stressed.
In any team project, there are bound to be problems, problems arise regularly even in non-team projects. The major benefit to having a team is to be able to use all of the resources of the team to solve these problems. In order to be able to utilize those resources for problem-solving you need to be able to communicate the problem and what you need to the team. If you don't communicate these facts, or don't communicate them well, you will be left trying to solve the problem on your own.
Ensures The Completeness of The Project
Without communication team members are working on individual pieces of the project and parts of the project are likely to fall through the gaps. When each individual is done with their work they will be left with parts of the project missing because they assumed someone else was going to handle that part. Communication helps to ensure that each piece of the project is done and that nothing is missing when the project is complete.
In the days of the old, it wasn't a major concern for employers that their employees be happy, they just wanted them to get the job done. Modern studies have shown that a happy worker is a more effective worker, though. This is especially true when it comes to working with a team. In order to keep team satisfaction high, you need to have communication. Communication fosters the feeling of working with other people and knowing that the members have the support they need.
Allows For Development
Part of the human nature is the ability to communicate but that doesn't mean that it comes naturally. Communication as part of a team allows us to develop professionally. We learn to be better team members, better workers, and better leaders through an ability to communicate. Without communication, it becomes very difficult to learn the various facets of jobs that we have never done.
Proof Of Work
Good communication allows project managers to know what each team member is working on. They can then in turn relay that information to their bosses. It allows the people above the team to know that the team is working hard. It also lets them know what the team is working on. This is essential because those above the team are often the ones paying the bills and supporting the team. Without communication, the higher ups will probably assume that the team isn't getting their job done or that the team doesn't need any more assistance.
Communication is a key factor in any part of your life but it is most important when you are working with a team. It allows the team to work more like one unit than like a bunch of individuals. Good communication skills aren't necessarily a natural skill, though, so it is important that team leaders work with their team to foster an environment of open communication. Once communication is open within a team, goals should be easily achievable.