This works with the list of characters as well. Often an executive may want to make a comment, but has forgotten the name of a lead character. With the board, the character name is sitting right in front of him. No, she's the hero's mother. He or she can easily make their comments, which makes it easier for them to get involved in the story.
Executives love to be able to contribute, and to tinker.
Having the plot up on a board makes it look like something that can be easily tinkered with. You get the idea. Our last few pitches using this system were on a project with DreamWorks, and involved Katzenberg, Spielberg, and Elton John. We tromped into the Four Seasons hotel with our board, feeling silly as usual, rode the elevator up to the Penthouse board room, dragged our board in and showed them the movie. We got calls the following two days on how well the presentation went.