Stop Brainstorming
I think the article’s missing an important trick: Brainstorming establishes a shared understanding (depending on the group dynamics, you might call it a fiction) that the group, not any individual, came up with the idea. That sense of ownership is psychologically important for aligning the group during the execution phase: People are usually a lot more motivated to implement a plan that they came up with, and if anyone challenges the idea, much more eager to defend it.