Sooner or later, the other people that have mixers will also be affected by this and will have to present themselves into the court even if they didn't laundered the money themselves because they have provided the services for the launderers to use, pretty sure that some people will still defend the use of mixers.
The charges in this case are because he conspired with darknet marketplaces to launder money, not simply because he offered a mixing service. Mixing your coins is not illegal and is done for a variety of completely legitimate reasons. The majority of coins sent to mixers come directly from centralized exchanges, usually from KYCed users, and so are simply individuals trying to stop these exchanges from spying on their transactions and financial dealings after they have withdrawn bitcoin from them, as all centralized exchanges do.
If "providing a service which criminals can use" is a crime, then you'll need to arrest damn near everyone on the planet, from Mark Zuckerberg to the guy who runs the hot dog stand on the corner. Just because a criminal can use a service doesn't mean running that service is a crime.