Maybe we should also ban gold and silver oh we use to trade in cattle so I guess we better ban cows too. If something has value criminals want it, it is honestly that simple.

Money laundering has been going on ever since the creation of trade. Even before coins were used. People had to pay cattle to the king or whatever and people could have "laundered" that cattle so they don't have to give cattle to the king. If some people can find a way not to pay for something they will.