Except that you are now committing your crime in a single jurisdiction and performing all elements of the crime at the same time. It makes it much more conveni

Except that you are now committing your crime in a single jurisdiction and performing all elements of the crime at the same time. It makes it much more convenient for law enforcement to catch and prosecute you. And what's worse they have incentive to get you to roll on your dealer. So they're more likely to hammer you with charges to force you to take a deal to testify. Compare that with my situation. You need to prove that I received the package, associate that shipment to an order, that order to a payment, and that payment to me. It's a multi-jurisdictional effort that would require subpoenas and some sloppiness by my dealer. And to what end? All I know is that I sent bitcoin to an address and drugs showed up some time later. I have no idea who I paid, where they got the drugs, who mailed the package or anything useful at all.