>I mean they use Blockchain, right? Isn't that like the only real requirement for the name crypto?

Absolutely not. Cryptocurrently exclusively refers to permissionless, decentralized, cryptographically secured, irreversible, fungible monetary system with a disinflationary or non-inflationary supply, following a voluntary, collectivized governance model.

A vast majority of tokens colloquially referred to as "cryptocurrency" couldn't be further from these principles. There are no stablecoins that are cryptocurrency. Ethereum is not cryptocurrency. Any coin issued by a corporation (e.g. Ripple) is not a cryptocurrency.

If your definition excludes Ethereum your understanding of the term so differs from everyone else's that we aren't talking about the same thing

Ethereum is a great utility token. Smart contracts absolutely have utility in the digital economy. It's just not a cryptocurrency, is all. It had a massive premine, there's no supply cap, it's subject to OFAC censorship, and has effectively demonstrated that just ~4.8% of the total ETH supply can vote to cause rollout and widespread adoption of a fork that reverses transactions.

We need different words for these fundamentally different things, because conflating them causes real confusion, as this very hack demonstrates. People are surprised that an admin can lock transactions precisely because the word "cryptocurrency" led them to assume properties that don't exist in stablecoins.

Where did the 4.8% number come from? Is it based on the validator stake? How does that compare to the number required to fork Bitcoin as a function of it's supply?

There was a vote after the DAO incident to roll back. 87% of those that voted voted yes (for the rollback), but only 5.5% of the total supply voted at all.

Those are all arguments for why Ethereum is a bad cryptocurrency, not for why Ethereum isn’t a cryptocurrency at all.

Is there even any currency that meets that definition? Iirc even bitcoin had some kind of reversal back in the day, or am I misremembering? I seem to recall bitcoin splitting in 2 for a while as there was some disagreement on whether the reversal should be made or not.

Idk, it's been a while and my memory is fuzzy.

Most blockchains nowadays are not proof of work anymore.