Putting 6 or 12 or 535 people in a room talking about the same thing does not make them smarter. Collectively, they are not the sum of all their intelligences put together.
In fact, when they disagree and jockey for position and power on that committee (board, council, congress) the quality of the intellectual output of its members diminishes quickly.
There is no “supermind”. There are only individuals with individual ideas, and differing measures of will to bring those ideas into reality.
One of my online classes called managing across cultures had a final online group project worth 50% of the grade. I took the lead only because I knew how easy it is to get bugged down with details and people like to be assigned tasks and tend to leave everything last minute. The group needed someone to make decisions, be firm, set the pace and dirrection, and involve each individual. Simple is good.
Committes are counter productive.