For people asking about Sybil attacks and how do organizations prevent someone from pretending to be many users, this is still an unsolved problem. One project that's working on it which has gotten a lot of support is Proof of Humanity:
Anywhere you'd point me for passionate pro-PoH takes?
Proof of Humanity is definitely still an experiment, but has a much more open and less authoritarian design. Of all of the "proof of personhood" projects it has the most traction, especially within in the Ethereum community where its founder, Vitalik Buterin, has written a lot about it, including in his recent post on Soulbound:
Sybil resistance is not easy to solve absolutely, it's all about degrees.