@neoxian, in principle, I really like this idea. Especially if it can catch "copy-pasters," as I have seen them on other sites... where someone will actually copy and paste what looks like a "real" 63-word (or whatever) comment to 100s of posts merely in service of gaining followers.
We have not yet had a wholesale influx of people from what I call the "I click buttons for cash" crowd... but it behooves us to be prepared for their arrival, because they don't care squat about community, content, the longevity of the site or anything other than how their next mouse click might earn 1c.
Might not sound like much of an issue, but multiply by a few million and you have a serious-- and potentially unsolveable-- headache. Talk about "dust" clogging the blockchain...