The point is it mitigates the on-chain attack surface which is still prevalent on PoW. Off-chain attacks are still possible for all consensus mechanism.
What on-chain attack surface? The only way to permanently knock a PoW chain offline is to consistently out-mine everyone else. In PoS, once you lose BFT quorum (1/3 of all votes), it's game over.
jude-|4 years ago
vbuterin|4 years ago
This is not how the Ethereum PoS chain's LMD GHOST fork choice works. If >1/3 drop offline, you stop finalizing, but the chain keeps growing.