You're right -- the traceable transaction ledger that most cryptocurrencies generate is exactly what this law is intended to force people towards, to ease the burden on law enforcement. Combined with basic know-your-customer laws, they're quite useful for tracking down illegal transactions.
Mind elaborating how cryptocurrencies are at all helpful here? How's government saying 2k cash transactions are illegal different from it saying 2k Bitcoin or Monero transactions are illegal?
The point is not that cops will now chase after conspicuous stacks of colorful paper, but that law-abiding citizens and businesses will refuse dealing with you and/or report you to police if you suggest to commit an offence.
How would crypto currencies solve this issue? Crypto transactions above that value are also illegal and traceable. If you wanted to break the law it would be easier to just keep using regular cash.
OR just use your bank account / card to send money, which is kinda like crypto but easier and legal.