Meaningful freedoms always include the possibility of abusing those freedoms. People will use the free exchange of ideas to advocate for falsehoods, start cults, and create political movements with terrible consequences. But they also use it to make the world a better place. New ideas that have advanced us as a civilization have generally started out as subversive and the freedom that allows them to grow to widespread acceptance is important. While the abuses are awful, and we can try to make the specifically abusive aspects illegal, it's hard to fully separate the good from the evil. In the end, the freedom to change to world for good always entails the freedom to change it for evil, too. But at least in this area, historically, the big wins wipe out the big losses -- and even if they didn't, I still want the wins.
This principle is true in almost every area of life. Strong encryption, for example, does help terrorists and cybercriminals, but it also helps revolutionaries and businessmen and ordinary citizens. I don't want to give too many examples because these things tend to be politically hot topics, and I don't want to distract from the central principle: meaningful freedoms can be abused, but are worth it because they also change the world.
I would say this is the case with cryptocurrencies as well. It is true that they enable certain criminal economies. Perhaps some of those economies would still function without cryptocurrencies, and perhaps some -- as the article suggests -- would no longer be viable. But cryptocurriencies enable people to build any economy they like without the approval or supervision of a state. There are places where the government does sort of a terrible job managing its money, where this is a major benefit to people. There are people doing things unpopular with some company or some government, who can still do them practically because of the economies enabled by cryptocurrencies. These people are by nature pretty subversive, and a lot of them are doing things I do not like -- but some are doing things I am very glad they are still able to do. Freedom's like that. Some people use it for evil. Some people use it for good. And the difficulties we have in all agreeing on what's good and evil (and the particular difficulties big governments and corporations have in getting the answer to that question right!) are why I'll almost always side broadly with freedom. When people use bitcoin to do criminal things, I'm all for prosecuting them for the crimes -- but leave bitcoin alone. The ability of people to run an economy without the government's permission is something I really like them to have.