> All the big players have got real-time feeds they're sharing with each other to keep track of who's made what transactions, and they're constantly reconciling

> All the big players have got real-time feeds they're sharing with each other to keep track of who's made what transactions, and they're constantly reconciling them against each other, to make sure that everyone's looking at the same picture. That is exactly what blockchain is. It is literally doing that. > None of this is strictly necessary, because there is a central source of truth that you can rely on. But who is running that? And why do you trust them not to change things around every so often? > it works a lot like how a blockchain would work Except there's no central source of truth because no one trusts anyone. Which is why its so strong. There's no need to trust. > The only difference is, nobody's bothering with all that crypto stuff, because all it would do is make the whole thing more expensive That's what makes blockchain immutable. You can't alter it without an enormous amount of resources. And even then, the actions of the rest of the network work to discourage that sort of thing. In PoW, everyone else is checking the non-altered data, and in consensus, everyone else has already agreed on non-altered data.