Wilfred Ruprecht Bion is an interesting researcher who has published a lot of work on group dynamics and he explains why and how groups fail to thrive.

W. R. Bion generally suggests groups are always calculated to fail because of a forced sense of cohesion that is only a cover for competing individual internal desires “unspoken private motives sabotage the public group effort to preserve the self in society.”
In my experience, groups spend a lot of time arguing over process and not in achieving end product.

It is easy to tear down and difficult to build up and those who cannot build up tear down.
Criticism works best when suggestions for improvement are immediately included in the commentary.

Groups more reliably find success when a hierarchical structure is imposed from an outside authority.

A Group Leader helps get things does as does mandating a clear method from outside the group for enforcing for decision-making beyond group unanimity.