The FBI has already proven pretty well that with a big enough dragnet (and resource that places like the NSA absolutely have), they can associate people to wallet addresses. It just takes slipping up a single time and they'll find you.
https://www.bnnbloomberg.ca/booming-crypto-market-a-potentia...
so not sure about the claim.
https://www.justice.gov/opa/pr/two-chinese-nationals-charged...
https://www.justice.gov/opa/pr/ohio-resident-charged-operati...
The upside of crypto currencies is decentralization, but a public ledger is public to law enforcement as well. With time and serious funding they often can link wallets to people.
I’m not saying it is good, only as a matter of fact it is a thing.