This would have the singular affect of forcing the entire cryptocurrency ecosystem into the black market, where it would thrive alive and well. Likely doing more harm than good in the process by fueling violent cartels to wreak havoc, as is still happening with the war on some drugs
It does make sense. There's a difference between say 50% of all crypto transactions being black market ones and 100% of them being so, and I don't think the 100 would be the same size as the 50 is now, in other words some of the legal trade would for sure move into the black market.