I don't understand this assessment either. How do you square this with, for example, people who have been able to obtain psychoactive compounds and other medicines that were previously unavailable to them?
And nice try with calling this contraband "medicines". The way to get legitimate medicinal drugs legalized is through careful analysis and discussions, and then you use democracy to make it happen. See California. What you DON'T do is invent some tech that wastes our planet's resources and invent some story about a decentralized future to fool regulators and then enable all kinds of illegal transactions, from human trafficking to terrorism, just so you can smoke a joint effortlessly.
There are plenty of legal things that are difficult to purchase with conventional reversible electronic payments. Off the top of my head:
Gambling deposits (yes, these are legal in most of the world but plagued by chargebacks from losing punters)
porn/sex toys (legal, but people don't want it showing up on their CC statements and don't trust these sites with their CC number)
"Suspicious" purchases with too much chargeback risk (eg. someone wants to buy a Macbook online with a US credit card and a Nigerian shipping address)
"Cash-like purchases" like buying a gold bar or some foreign cash online and having it shipped to your house. The margins on these types of purchases are too small to cover the credit card fees and the chargeback risk is too high because it attracts carders.
I could probably go on, but if you don't think irreversible electronic cash has any legitimate applications, you're not thinking hard enough.
I actually don't think blockchain-based ledgers are irreversible. The most exhaustive account for how these ledgers are reversible is captured in the Blockchain Folk Theorem paper [0]. We can brainstorm all kinds of fun use cases for irreversible digital cash, but given the growing evidence, I don't believe such digital cash exists.
[0] https://www.tse-fr.eu/sites/default/files/TSE/documents/doc/...
Drug prohibition is not the future of humankind.
If blockchain tech can more quickly undermine it, then I don't think it's reasonable to say that it has no role in making the world a better place.
Additionally, if blockchain tech can substantially undermine a policy entrenched with corruption and enforced by violence, I think it's reasonable to surmise that it has other, less controversial use-cases as well.
The current state of development in this field suggests that I'm right - again, see the technologies above; it's not obvious how they're possible without a distributed consensus mechanism.
I also think that the remark "smoke a joint effortlessly" is both a silly ad-hominen and a red herring. I have been effortlessly smoking joints in all sorts of jurisdictions for the past decade; the change in law really didn't do much to enable that any more than it was already trivial.
However, if I were a member of a less privileged class and wanted to retain some anonymity, or if I wanted access to a more esoteric plant or compound and didn't have the social connectivity to obtain it, then I think that I'd find a mechanism to subvert these prohibitions very helpful.
Not everyone has the same opportunities and protections as you. Your implicit suggestion that everyone simply live in California is very insensitive. Technologies that tend to smooth this disparity are reasonable to celebrate.
You're right that some nations will be more oppressive than others, but you're forgetting that those places will more easily ban public blockchains than in places you've hinted don't need it. See Pakistan, Bangladesh, or China as examples.
So you either live in a place where you can fight for your right at a political and social level, and don't need the blockchain (eg. USA), or you live in a place where you cannot easily affect policy, in which case your government has probably also decided you cannot use tools that would circumvent their enforcement... such as the blockchain.
