Is there any point to mixers?

Every once in a while a mixer gets sanctioned or a DW vendor gets arrested because of money laundering, but the government is always able to trace the funds even through XMR. But it doesn’t really matter because eventually one would want to spend the crypto but in order to spend it would have to be sold for USD creating a taxable event with no purchasing history. So what’s the point of “criminals” adding a couple steps in the ledger if they can’t ultimately get their btc off chain and freely able to spend?