I think it’s more direct to point out that they weren’t hidden, they were public and that’s how authorities found, traced, and convicted them. Tracing the dollar stops at each institution and they may or may not persist an audit trail.
The entire concept of laundering money is based on the inability determine the origin. The only way this can be accomplished is by exploiting known transactional blind spots such as cash.
Therefore, we can firmly state that the antiquated concept of using untraceable value stores such as cash as tender that is infecting crypto.
In closing, the argument represents the logical fallacy of “false cause” in that crypto does not cause criminal activity. In fact, the ability to instantly and publicly trace transactions with ease in conjunction with the history and background of those making this claim lead to a more insightful conclusion. The ones who are making the claim are the criminals and they don’t want the transparency that crypto currency represents.