It's not only about morals.

No, chargeback rates are not the only reason banking companies like Mastercard are dubious about adult content. In 2021 they added contractual terms to ensure that adult content uses age verification, has the consent of the participants, and to remove illegal content before it is published at soon after it is reported.

But also, the financial industry has a history of discriminating against their customers based in moral reasons (or at minimum bowing to regulatory pressure which stemmed from upstream morality decisions).[1]

[1] https://www.vice.com/en/article/pa8xy9/is-the-doj-forcing-ba...