Joanna Neborsky Blockchain, the ingenious database technology best known for underpinning the faddish digital currency Bitcoin, is reviving the utopian fantasies of the early internet era. In an influential manifesto from that time, “A Declaration of the Independence of Cyberspace,” published in 1996, the essayist and activist John Perry Barlow opposed the idea of government regulation of the internet, offering instead an anarchical vision of an online world in which a decentralized network...