So, you basically described how steem works.

Every steem power you have represents your ownership of the steem blockchain.

But since here we can only influence through upvotes and downvotes, and only the rewards, your idea kind of expand the steem concept.

It would be as if you could use your steem to vote for a mute/ban/create sections/whatever other function was needed.

It is a good idea, it should basically how communities should actually be implemented.

You trade sbd (not steem) for a token of a community, now you have the power to influence on it though votes proportional to your stake.

Too bad it won't happen.