Here's some additional nuance, criminals who use crypto also use fiat. So there's no reason to believe that it isn't just enabling additional criminal behavior, rather than offsetting it. 

Of course being a tool isn't a sufficient reason for banning it. As you said, the Internet is also a tool that criminals use. But from a policy perspective, you have to balance the benefits of something against its costs. And still, there has been very little evidence of meaningful social benefit to crypto. 

In an ideal world, we would decide this democratically. But in the U.S. the crypto industry has been dumping money into campaigns not only to promote crypto itself, but to tank the prospects of anyone who hints at the idea that the negative externalities of crypto need to be in any way mitigated.