[melolife]

Open membership is arguably a worse problem than stake requirements, as PoW participants do not have a vested interest in preserving the integrity of the chain. Ethereum 2 actually throttles validator entries and exits for exactly this reason.

As an example, any sufficiently powerful entity can temporarily and affordably commandeer computational resources with the intention of disrupting the chain.

Under PoS doing so would devalue your (presumably enormous) stake, so participants are at least incentivized to act in the interest of the chain.

[jude-]

Open membership means that the chain stays alive as long as anyone in the world wants it to. This isn't true for PoS chains -- you must to acquire tokens to keep the chain alive.

> As an example, any sufficiently powerful entity can temporarily and affordably commandeer computational resources with the intention of disrupting the chain.

A sufficiently powerful entity can DoS enough staked nodes that quorum can't be reached, and thereby force a PoS chain offline indefinitely for far less energy. If they're clever, they'll buy some PoS coins first, so that once the offline nodes all get slashed, they'll be the majority staker.