They could have blocked sending to the account at 2 million or 3 million.
Could they? I though this was a decentralized system where nobody could block other people's transactions. I think you got that wrong actually.
They have some obligation under international law to protect their users.
Steemit is just one of many interfaces to the Steem blockchain. The blockchain is immutable and censorship-proof. This is one of its selling points and I'm surprised you are not aware of this. But it also has the corolary that there is no central authority to protect you from scammers. What we can do is raise awareness and try to protect people from being scammed.
Of course, steemit it could indeed implement popups that warn you about known scammers, but I think this will go against their decentralization ideals at least to an extent.
After the huge @bellyrub scandal and scam if you try to send to that account you see this:
"Use caution sending to this account. Please double check your spelling for possible phishing."
They at least red flag the account as a possible scam. There is nothing still after MILLIONS stolen by poloniex.
So I'm wrong and you are right. They are willing to do this and it should be done for this exchange. I guess they are afraid to alienate one of the few exchanges trading steem.
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.