I found this MSI research on Product Ideation in Social Networks very instructive. Please note particularly:
“These findings suggest that denser, tightly interconnected communities—which are very typical in online communities and social networks—are counterproductive to the generation of more-innovative ideas. This implies that managers who use online communities and networks for ideation purposes should reconsider how they allow consumers to interact. “Engineering” networks that allow for many connections that are relatively independent of each other is likely to lead to optimal outcomes. However, the current practice of allowing consumers to be tightly interconnected is likely to lead to underperformance and, overall, less creative ideas.”
Please note also the What factors facilitate collective intelligence? section of the Handbook of Collective Intelligence.