And I thought I was doing something wrong! I even verified a credit card and my bank account with them. Maybe we should let Coinbase know about this, I don't think they would allow it.
I created a support ticket and explained the whole situation to them. The ticket was answered today, so Coinbase is now aware of the scam. If you opened an account using the scammer's affiliate link, I suggest that you CLOSE THAT ACCOUNT (that option is under Settings > Security), then clear your browser's cookies and open another account if you intend on keeping using Coinbase.