I think you did the right thing brining forward your issue. If group admin is given the authority to select the posts which should be given the booming support according to the given guidelines. No one should question his decisions if he follows the given guidelines. If there is a problem in guidelines , it should be updated .

For example : Only one member from one family is allowed to use steemit. lol

It only need one update - 1 booming vote for 1 member for a week. This will make the votes more distributed among the members.

Taking decisions listening to inbox will ruin this platform. It's not the way how a proper management manage something. It should be worth enough to take quality decisions for the sake of every one in a community. They should understand they need everyone.