I'm definitely not a lawyer.
> Is there no legal difference between merely having intent to commit a crime at some point in the future, and actually attempting to commit a crime?
That was my point. To be charged with and prosecuted for a crime you need to both intend to commit it and then actually/attempt to commit it. Attempted murder is a crime, I both intend to kill someone and try to do so even if I fail. It's not punished as severely as actual murder but it's still a crime. But attempted murder is actual a specific crime in the criminal code. There's elements of it that need to be proven in court.
Unless a jurisdiction has a crime of "attempted possession of marijuana", intending to buy marijuana but ending up with oregano isn't a crime someone can be charged with. If we start writing laws outlawing attempted possession it's a slippery slope that gets into outlawing thoughts. It also opens the door to stupid pre-crime ideas like someone would only use cryptography to get ahold of illegal content therefore anyone using cryptography is instantly guilty of attempting to get illegal material.
You can be sure this is what will happen because it's the very arguments the anti-cryptography groups use.