There are several reasons.
1) Groups are often more creative in less time because of multiple brains working on the problem.
2) What one person doesn't find clear and easily understood, one or more of the others may.
3) When you understand the action of the group you are more comfortable with the outcome and very likely more supportive.
4) The accumulated experience in several individuals provides more data and understanding than is possible in an individual.
For these and many other reasons, businesses are looking for employees that can communicate well and work together in groups to solve problems as quickly and effectively as possible.