The most amazing assertion is Amazon saying that they had to give in "because Macmillan has a monopoly over their own titles." Well, duh. As blogger and author Lee Goldberg says, that's like complaining that Nabisco has a "monopoly" over Oreos. Hello, Macmillan puts out those books.
The article also says that Amazon has done this before. "In 2008, it removed all titles by Hachette Livre U.K. on its U.K. website in a dispute over its demands for better terms."