To be clear:
DreamHost has occasional promotions to commemorate significant events like their anniversaries and their achievement of various hosting milestones. In these promotions they will advertise a promotional code on their website.
DreamHost has an affiliate program where current customers (and anyone else for that matter) can get referral fees for referring new customers. In order to help you attract referrals, they allow you to create promotional codes that give new customers discounts or extra services and features for free. The cost of these discounts/services/features comes out of the referral fee itself.
It's become common for people to create max discount promo codes that discount your first year's hosting by $97. This matches the entire amount of the DreamHost referral fee, so the original referrer gets no referral fee in this case. Best guess is that most people are hoping for secondary referrals (you get $5 for everyone your referrer refers).
The original DreamHost promotional codes have always been better than the equivalent referral promo codes, though some referral promo codes may have a set of features that is more suited to your needs.
Hope this explains everything clearly. I didn't want the OP to be left out if they're new to the idea of DreamHost promotional codes.
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