If I show up to a drug transaction anywhere with a hardware wallet, I think I'd get laughed out. Yet that's not the same with USD. Or in the extreme case, If I went to Libya to purchase a slave it is safe to say they take Euros.
So while you can buy a few grams or a slave with a briefcase of notes, it's not as easy for the dealer.
Crypto, if safe, would lower the risk by about 50%. Bitcoin is traceable but it seems that something like Monero might be better for this.
It's for wholesale drug operations. Usually drugs go at one time, money comes back another time. Only now instead of cash you could just use a crypto, but figuring out how to liquidate enough of it would be difficult.
Not liquidating it all would be advantageous I'd think.
OTOH the DEA would love the traceability.