if amex:

• 1) allows self referrals (i.e., 20k MR referral bonus for those referring themselves from the business gold rewards to another card);
• 2) allows you to pick any card once you have been referred;
• 3) usually doesn't do a hard pull on existing cardholders;
• 4) doesn't subject charge cards like the business green to a "number of cards" limit;
• 5) waives the annual fee for the first year on the business green; and
• 6) doesn't report business cards to the credit bureaus,

what exactly would be the downside for referring oneself to the business green, even if you are ineligible for the signup bonus, just to get the referral bonus? is there a limit to the number of times you can do this?