Update: you can no longer use credit cards to load this product.
It's always good to have a few tricks up your sleeve for Manufactured Spending. If you need to spend a few thousand dollars for a credit card sign up bonus and you don't have access to more lucrative Manufactured Spending options, how can you do it quickly and inexpensively? What happens when RedBird no longer allows credit card loads and you were banking (haha, get it?) on using that? This is where your Emergency Manufactured Spending comes in.
In addition, some techniques like Nationwide Visa Buxx and American Express Gift Cards are not useful with Citibank credit cards since they will code the transaction as a Cash Advance.