It seems so obvious when you see it in print (as JadeDragon illustrated): If you don't submit articles, they won't sell. If you don't continue to submit articles, they won't sell.
As far as the referral system goes, I don't think it's worthwhile. I've recommended a few friends (who are also writers and far better writers than I am) as well as have built a network of over 50 other people who have signed up under my referral link. I've earned just over $1500 in referrals with most of those being generated by my friends (and this dates back over five years). How did they get the chance to earn most of their CC profits? I referred them to my clients when my clients needed extra help. Of the 50+ other writers who have signed up under my link, I have earned about $80 or so. As JadeDragon mentioned, the vast majority have done absolutely nothing other than signing up. I have two that I know of that have sold a couple of articles which accounts for that $80 or so figure -- probably less but that's my fuzzy math).
While I don't mind referring my trusted writing buddies to my clients, it's not like that $1500 fell on my lap simply by placing a link on my blog. I had to work to convince my writing friends to join CC in the first place, show them the ropes, help them understand various client expectations, and more. I actively helped them find good requests and recommended them to clients as mentioned earlier. I reviewed and critiqued their articles before submission and soothed their frayed nerves while they waited for acceptance or dealt with article rejections. Did they stick around CC? Unfortunately, no. CC was fine for a while but none of them are active here anymore. No hard feelings, but would I do it again? I'm not so sure. I would definitely help a writing friend that wants to make a solid go of CC but am not overly interested in helping those with a casual interest.
So, how do you make money at CC? According to my experience, not by referrals. Submit, submit, submit. That's how
Edited to add: While I understand why CC wants an affiliate/referral program, I'd prefer to opt out of it and be able to keep that 5% earmarked for referrals. Now that would make a difference in my life!