Earlier quoted context omitted.
Private blockchains. Imagine a crime cartel with a private blockchain. Obviously they are not KYC. You can withdraw funds from the cartel, or pay for cartel services with the coin. Ironically, a version of this was in private fiat currency - the coins in the John Wick movies were used this way.
That's still a traceable blockchain though, just privately kept. As soon as you start keeping a ledger, you make transactions traceable. With a single or low number of ledgers, network analysis becomes easier the more heavily each actor uses the currency as well, compromising anonymity.
For an example, most cryptonote networks function this way unless they have explicitly damaged or disabled the functions responsible, like in the case of Electroneum.