I think it is a matter of choice for the managers, If a manager thinks that the discussions from a board is important to the project he is managing, he can permit and agree to count post made in those places by people under the project as valid. Some managers also see that some places in this forum make people lazy in how they post, so to make people to be committed to writing well they exclude and tell the people under them that post in those places will not be eligible even if they post there. It means you can still post there if you want, but it will not be eligible to him.