If some marketplace works without KYC, it will never cooperate with the state regardless the subject of complaint. It is very naive to think they will obey privileges granted to you by the state (so called "copyright") and reject other complaints regarding drug sales, money laundering, weapons for terrorists etc.

Semi-legal marketplaces have no practical sense in real world: you have either to operate anonymously and reject any state's intervention or obey ALL laws including KYC.