These companies can't update the documentation to reflect the changes and enhancements which they have made to MySQL. I can't take the docs and publish changes or annotations without violating the license agreement for the docs.
If Sun wants to claim that MySQL is true open source then they must open source the documentation. If Oracle wants to claim that there is plenty of competition in the database market, they should be forced to open source the documentation.
It boils down to this: The current documentation license scheme hurts a fork's ability to compete in the market by denying them a core part of the MySQL product - the documentation.
If the playing field isn't level between MySQL forks and Sun, how can their be a level playing field in the rest of the market?