You may be thinking of “federation.” Ethereum is both distributed and run in a decentralized fashion. It uses something like the GHOST consensus protocol. Nodes don’t need to trust each other.
If they were just a state machine, they'd be useful.
They're meant to be a pseudo physical state machine where changing the state takes real work. If you decoupled the needless work aspect, you'd probably end up with a useful value proposition (which no one would adopt)
Decentralized systems matter but they do away with a single source of truth, that's what makes them responsive. They have local consensus, not global consensus. Torrent networks are decentralized, protocol based chat apps are (riot/matrix), Mastodon is, and so on.
When articles like this say that performance of crypto networks is a 'technical problem' to be solved I don't think they understand that it's not a problem but a necessary and intrinsic feature because to maintain global consensus in the absence of an authority you need to impose costs on the users of the network. That's why crypto systems aren't comparable to the decentralized web.