Why are they paying money? Don’t they have it in their contract that they can dump you at any time for any reason?
I’ve been dumped for not using a card enough. No warning. Just, “Your account has been canceled. Bye.”
The only way it makes sense is if the people receiving the offers owe a TON of money to Amex, and Amex is hoping that the $300 offer might prompt them to actually pay off their debt instead of default on it entirely.