American Express asks you to refer only people you know personally, so posting your referral link publicly puts the bonus at risk.
What it is
Amex positions Refer a Friend as exactly that. The program terms ask Card Members to send their link to close friends and family rather than the general public, and the referral flow separately requires consent before you send an invitation by text. Posting the link on a website, a forum, or a public social account runs against that, and the cost of getting it wrong falls on the person who shared the link rather than on the person who used it.
Why it matters here
This is why Dealaka publishes what an Amex referral pays but hosts no Amex referral links. We describe the program and link the official terms so you can read them yourself. Where an issuer's own terms do permit public sharing, we say so on that program's page. Where they do not, or where we have not yet confirmed either way, we treat sharing as restricted.
Reading the terms yourself
The full Refer a Friend terms are shown on the referral page inside your account, keyed to the specific Card you are referring, so the wording you are bound by is the wording you see there. The public program page linked below is the starting point. Terms are revised without notice, so check the date on any summary, including ours.