We’ve discussed this internally in the past. One issue is that if you make the referral program open (anyone can join onchain permissionlessly), someone will set up a “cost plus” registration UI that gives the buyer the referral fee, so you’re just back at the status-quo but with slightly cheaper prices. If you make it permissioned (so only an allowlist of referrers are allowed), you have to have some kind of committee to decide who qualifies.