That's not true, you can check ANN thread in gambling board, many of them post their referral link.
Yeah I can see that. But maybe this will be allowed only once right during and upon one time posting only. After that, it someone can report it for violating rules if ever got posted again in linked thread or other threads since its about spam.
The punishment only make his thread deleted, it won't make him get banned.
I see anyway thanks for clarity with this, with theymos message it seems that its totally fine as long as the content is more noticed than the selling ads(ref code?) is that what he meant on that context.