We already had that when Hive Blog first started. My referral code was my username, and if you wanted to use it, you'd have to get in through Hive.io or Peakd if I'm not mistaken. Then they stopped it. InLeo also has similar referral links with that kind of reward tier. I don't think the rewards were very well distributed because of course people were abusing the system but also trying it out for the first time just to see.