It’s that grind which is fatal for mixers, not unlike Tor exit nodes. Nobody _needs_ to use them except money launderers but they depend on benign traffic for concealment. Even most privacy-minded people are going to hesitate if it taints their ability to make transactions with regulated businesses and the less innocent traffic there is, the more likely it is that using one will attract scrutiny, accelerating that feedback loop since most people don’t want to deal with the risk even if they are totally innocent.
The other level to consider: this mentions DPRK. That means all of the intelligence agencies could be involved and that increases the odds that a mixer is compromised or even run by them as a honeypot. Think about how you can decide whether to trust one, and whether the odds are that you’re signing up for additional privacy invasion like the people who’ve used certain messaging systems or VPNs.
Fixed it for you. There's a tendency, particularly in the USA for people to assume that their law is universal
Ethereum isn't being sanctioned. Tornado is. If you transact with Tornado, you're in violation of the law. If you don't, you're not, whether you use Ether or not.
> if the government said “we’re now keeping a database of cash serial numbers that are hereby banned” would everyone need to install the “cash checker” app and scan each bill they receive?
Law enforcement has long used marked bills [1]. The cash isn't "cancelled." If you randomly end up with one, you're fine, in the same way that if you unknowingly end up transacting with a wallet that transacted with a wallet that touched Tornado, you're also probably fine. But if your garage has a box of marked bills, or if your wallet did a big transaction with another wallet that does lots of Tornado activity, you're going to be on law enforcement's radar.
[1] https://en.wikipedia.org/wiki/Marked_bill#cite_note-4