The original idea/reason for this mechanism on steem was two-fold:

• to give bonus for curators that find out a gem, and promote a post, that others find worthy as well
• to give an incentive for the curators to decide whom to vote a bit faster, so the author gets a feedback sooner

These two ideas sound fine, but turned out to be too easy to exploit with automated voting pools..
I considered them for a while few years ago, still on steem chain, but it's pretty hard to implement those two ideas and making them resilient against a similar exploitation :/