Yes,  as I mentioned in these way the people who are fraud can reverse the payment. Even almost maximum time it will be auto reverse without any dispute (for fnf payment there is no dispute option), but when they create dispute via bank or credit card issuer then paypal will create dispute on behalf of the bank or credit card issuer. Many people choose fnf option as---
1. Maximum fee is 4.99$ from usa paypal to other
2. Many people do not know it is reversible if receive by fnf
3. it does not hole 7 days or 21 days or something like this.
4. Fee deducts from sender
5. Only fraud people can reverse. General public cant reverse.
6. There is no dispute option. There might have more reason.