TW: Aaron Wall the "seobook" basically claimed that AdSense referral sux because there exists too many penalties for those "slow earners". He is talking about the new $100 in 90 days recently discovered by JenSense. Personally I have never made anything through the AdSense referral (and probably never will), however I can understand why Google does that. They are not charities -- the Big G, as a public company, shouldn't hand out $100 for every Joe Sixpack you have introduced who only has a 2 page site on GeoCities. They have introduced their referral program, hoping that it might bring in more big traffic publishers, i.e. more money to them.
At the same time, a new site that makes $2 per day (which won't make Google referral payout requirement) might be brining $2,000 a day in 12 months time, keeping both the publisher and Google's shareholders happy. Who knows. Except the original referrer who missed out on the reward.