To clarify, the US sanctions on tools but not target specific entities or groups of people.
So why bother to sanction something that the government probably won’t be able to sanction in the first place?
What is a mixer?
A cryptocurrency mixer, sometimes referred to as a tumbler, is a tool for money laundering. The sole purpose of the invention is to make transactions untraceable.
How to mix?
Even crypto is pseudo-anonymous, but it is traceable through your wallet address. A mixer is a black box service to filter your traceable wallet address into the untraceable wallet address.
How to wash your money clean in the traditional way?
The assumption is you will not get caught at each stage, and then you place your dirty money in a bank through companies and use the funds to purchase legal goods like houses or luxury goods.
There are mature regulations and rules to stop you from putting your dirty money into banks.