the role of advocacy groups

i was struck by this story the other day about The Defence Industries Council.
They came out and said how wonderful their members are for the economy, and their work being simular to mine, it caught me.
their job is to promote their members' interests. and they did.
their job is advocacy, not balance. it is important that politicians are able to take their argument as part of the whole picture, and are not caught up with one group. Even when it's me