What does this mean? Is there a central node in PoS, or are they saying that power is proportional to stake size?
Note that PoW works exactly like this too, except far worse due to economies of scale. Purchasing mining facilities in bulk will give you a much better deal than buying rigs as a home miner. Whereas in PoS, both the ultra-whale (1000 ETH) and mini-whale (32 ETH) are earning the same exact % return on their investment. The average user delegating in a staking pool is also earning fairly similar return to all validators (with some % of their return paid to validators for their services).
I do not think the claim that PoS is more centralizing or more “rich get richer” than PoW is necessarily true.
And there are theoretical solutions to this as well; projects like Bright-ID are working on proof-of-identity / proof-of-humanity.. maybe we'll see a proof-of-stake blockchain with governance tied to identity in the future? This could even be combined with zero-knowledge to ensure voters are unique humans without making their wallet<->identity associations publicly discoverable (though there may be situations where this is desireable as well)
This is what I'm hoping for. As soon as this proves viable, this opens up the door for things like automated international UBI.
As for the rich getting richer, that's no different from mining. Stakers have much lower ongoing costs, but the rewards are lower too so their percentage annual return isn't necessarily better. And everyone gets the same return so there's no economy of scale, which is not true of mining (or, for that matter, savings accounts).