No idea about original reasons, but I can imagine a projected chain of reasoning:
there is a finite number of conjunctive obstacles
if a single person can only think of a subset of obstacles, they will try to solve those obstacles first, making slow(-ish) progress as they discover more obstacles over time
if a group shares their lists, each individual will become aware of more obstacles and will be able to solve more of them at once, potentially making faster progress
No idea about original reasons, but I can imagine a projected chain of reasoning:
there is a finite number of conjunctive obstacles
if a single person can only think of a subset of obstacles, they will try to solve those obstacles first, making slow(-ish) progress as they discover more obstacles over time
if a group shares their lists, each individual will become aware of more obstacles and will be able to solve more of them at once, potentially making faster progress