Okay then. That's a fair point.

Exactly. You know what else is used effectively for both privacy and avoiding taxes? Plain old physical fiat cash, and yet that doesn't mean it is illegal to use cash. Just because a thing can be used for illegal purposes doesn't make the thing itself illegal, so long as it can also be used for legitimate purposes. Then there is the deeper question of whether those so-called "illegal" purposes should really be considered so at all.