Bitcoin can prevent crime but not much if we see how many transactions is linked to criminals and illegal buying. I think that the biggest problem is that a lot of criminals is using bitcoin for illegal trade.
It's a fact that bitcoin is being used in many illegal things like buying drugs, weapons, etc. without being recognised but I don't see why bitcoin can prevent crime. I think that you missed a "not" or something because it's clear that the number of people using bitcoin in illicit stuff is still high and there is no way of stopping it. And it makes no sense just for a currency to stop crime once and for all.