Our friend Rothbard. Nice recommend. Note, I'm referring to ID or "reputation" in a decentralized world WITHOUT a state. Or as "without" as is practical.
Example: Say you want to lend money to someone else. P2P investing. You'll want to know who they are, their history, and trustworthiness that they will repay you. Sure, you could scour their social reputation (online + offline). But if they're like most scammers they could just close up shop, rebrand under another name, then rug-pull over and over again.
An "immutable" reputation or "identifier" could solve this, by pinning undesirable behavior permanently to the person in question. Not state-run. Open source. But it also creates problems too. Big topic. Love to hear all thoughts.