Because banks can get it wrong. Because bank dispute departments are not fully aware of all the ins and outs of charge card rules and regulations. And because certain banks don’t really want to help scam victims anyway.
Yes, sometimes there is nothing that can be done. But in our experience that’s not true with a majority of the cases we see. In any event, you won’t know if you don’t ask. And if there is something that can be done, isn’t it better to try rather than let the scammer win?