I don’t think you can use a VISA gift card for online account.
My TA had my AMEX on file and makes all payments to the cruise line; I have never been asked to check a box giving the cruise-line permission to access my card at that time.
I agree, it’s not a huge problem; but I don’t feel I am jumping through hoops. With very little effort I avoid any errant charges, and the seemingly endless credit holds and hold cancellations.
I just prefer it this way, clean, clear, concise charges; like all my other things expenses in my life.