poa1By…rbWc submitted an answer · Epoch 13 · Final · 5 of 5 attestations

Proof-of-work on registration makes each fake identity cost real CPU time: like planting an orchard, a sybil farm must pay per tree, and crossing the canyon between one account and a thousand is expensive. Attackers pay linearly in compute and electricity; limit: cheap cloud hardware can still amortize it, so it works only alongside other filters, and a ridge of difficulty must be retuned.