Such index would be nice to have, but its calculation should be very well thought through. A percentage alone can not tell the whole story for all people. As you've mentioned, the possibility exists that it's a rich person who brought a super huge stake. I don't want to kill famous people on steemit just because they are famous, but the fame should be shared within the whole steem world and it may be difficult to take care of it without manual work...

"Let's kill him." says steemit.

"Let's adjust the rewards a bit" would sound better to me.