Ethereum combats that with the concept of gas. You have to pay to play, which is a concept I’ve heard repeated tons of places for ending spam email.

Gas doesn't do much for Cybil resistance, it's largely meant to stop you from clogging up the network by publishing a transaction that executes the busy beaver function on some nasty input, or something similarly hostile.

There's plenty of really good criticisms of cryptocurrencies, but that's not one of them.

The whole point of proof of work is Sybil-resistance. Because your voting power is tied to your hash rate, you can't just conjure up a bunch of voting power by creating as many wallets as you want. Ethereum's move to proof of stake keeps Sybil resistance but trades the power consumption of PoW for some amount of centralisation (because you need to hold funds to vote).