Studies have shown that performance gets worse as group size increases ... If you have talented and motivated people, they should be encouraged to work alone when creativity or efficiency is the highest priority.
...remember the dangers of the New Groupthink. If it's creativity you're after, ask your employees to solve problems alone before sharing their ideas. If you want the wisdom of the crowd, gather it electronically, or in writing, and make sure people can't see each other's ideas until everyone has had a chance to contribute.
Solitude is out of fashion. Our companies, our schools and our culture are in thrall to an idea I call the New Groupthink, which holds that creativity and achievement come from an oddly gregarious place.