I've only read the summary but Philip Tetlock comes to this conclusion based on his work with "The Good Judgment Project" (described in his book "Superforecasting").
The GJP is a kind of experiment he's been running for a few years in an attempt to learn how to improve predictions.
From what I remember: overall, teams did better than individuals and wisdom of the crowds because they were able to feed off and combine each other's points of view and separate knowledge.
However! It's important for teams to not let groupthink dominate—individuals within teams needed to challenge each other.
The GJP is a kind of experiment he's been running for a few years in an attempt to learn how to improve predictions.
https://en.wikipedia.org/wiki/The_Good_Judgment_Project
From what I remember: overall, teams did better than individuals and wisdom of the crowds because they were able to feed off and combine each other's points of view and separate knowledge.
However! It's important for teams to not let groupthink dominate—individuals within teams needed to challenge each other.