How could decisions made by Graham’s management team be subject to groupthink?

Graham ruled with an iron will. He felt that the only way to motivate his employees was by giving them clear direction and having them keep him informed of their progress. He had full confidence in his abilities and believed that his employees respected and liked his management style.
This belief was validated in almost every meeting: He would present his agenda and state what needed to be done, and everyone would happily agree with him. Well, almost always. One time, during a department head meeting, the new director of maintenance publicly disagreed with him.
That discord was short lived, as Graham made it clear that his opinion on a topic would stand.
Recently, Graham and his sister were discussing a Harvard Business Review article titled “Three Tips for Overcoming Your Blind Spots”
(Dame and Gedmin 2013). His sister, who was studying leadership, suggested that all leaders have blind spots, which cause them to believe something other than reality.