If I'm a whale I can make $1k/week upvoting comments. I make more when I upvote successful posts early.
I think this touches on what I find to be an annoying flaw; people are incentivized to upvote new content before they even take the time to read it. Heck, Steemit kind of doubly incentivizes this by putting upvote buttons on the feed pages rather than only on the article pages themselves; it's trivial to upvote a post without even being able to read it if you wanted to! (And, of course, I'm sure we've all seen "great post" comments on long articles ten seconds after they were posted; you know there's no way the commenter had time to read the article yet. But that's another issue.)
I'm not really sure what the solution to this would be; your solution may help the cases of whales circle-jerking, certainly, but I'd like to see the more broader behavior not be encouraged so much somehow.