And still the question is where are the rest? If they track Takayoshi Doi getting it from someone in the dark web then they can definitely identify the source.
A lot of it is long, long gone. I followed it at the time and the hacker was seriously brazen and was not hanging around. They were laundering it through services who refused to confiscate it, or just claimed not to particularly care. They also had some sort of tor shopfront selling it at a deep discount.
Anyway, IMO, banning cryptocurrency in Japan will not help to them to derecrease scammers. Believe me, they don't ban crypto on japan.
The seller didn't hide everything, actually they open a website and broadcast everything. So if you are a serious buyer and knowingly that you are buying a stolen crypto, would you risk it as you are going to be identified? And during that time, perhaps they thought that they are not going to be found out by the authorities.
And if you are the buyer, of course they will also "suspect" you as one of the hackers, just basic investigation theory.
So if you look closely though, it's not that Japan are going to ban crypto, they have legalised in 2017. What the article says that crypto being bought from the Coincheck hack are going to be ban, two different thing.