Mixers only make it harder for your mixed coins to be traced. It's highly probable that, if I ever commit a mistake and somehow link my coins to my identity, I will mix them afterwards for no illegal reasons. Wanting to have privacy is not illegal activity. This applies to everything: using cash instead of card, old Nokia phones instead of Google-infected "smartphones", Signal instead of WhatsApp etc.

Some people use burner phones for avoiding having their main phone number found out. The fact that drug dealers also use burner phones doesn't mean the former guy should not have access to purchasing them.

Saying that cash is helping the society more legally than illegally makes me smile. I can't even imagine how much cash is used every single hour in tax evasions alone. Romanian bars do this on a regular basis: take the customer's cash but keep it in your pocket and don't print the paycheck so that, as a business owner, you don't pay taxes for your earnings. There are probably so many billions of money in cash all around the world that are cashed in on a monthly basis without taxes being paid.

Everything is going to have an illegal use case as long as criminals find a way to do it. Probably even soap or rubber ducks. Even after we get CBDCs and cash goes out, there will be other ways to do illegal stuff without being on the radar. We simply cannot have the perfect thing. You can't have freedom but not have it. You have to choose between the two.

Remember, mixers are only there for improving your privacy. They do not support illicit activity, as far as I am aware. And my personal opinion is... even if mixers were used in a significant percentage for illegal activity, banning them means taking away my right to privacy. This is what people don't get: we're literally setting our own right to privacy on fire by wrongfully placing privacy and crimes in the same pot.