IMO the same is true of Tornado Cash and digital currency in general, even though it is often overused by criminals. I have heard strong arguments for each of the following being used primarily or only by criminals:

* Tor & encrypted messengers: the whole "going dark" paranoia from mid-2010s

* Knives, guns, explosives: mass shootings and domestic terrorists; "nobody needs military style weapons"

* recreational drugs: see the War on Drugs which is really a war on poor non-White people

* cash: see the death of the €500 note

* masks: see the anti-mask laws intended to target the KKK

Note that I'm not claiming that society should never be able to regulate tools. Certainly I don't want the disturbed guy down the street making Ricin in his garage. We should keep in mind though that the tools themselves are value-neutral; it is the people who use them that give them a value.