They are running a social media network no matter how they classify themselves as bogusly decentralized or centralized. They could drop the social media description I guess and that could then indemnify them from having an obligation to protect their users.
Since their self-described as a social media platform they have an obligation to protect their users against known scams. How they choose to do that is up to them. Inaction is not acceptable.
What's magic about social media that it places a higher burden of user protection that another type of website.
Don't got me wrong, I absolutely view this as a huge problem, I just don't expect them to act the way you are hoping and I see that they have their reasons. I'm not even saying their reasons are valid.