Reading through the linked article on "real world uses for Web3", most of them seem to consist of things that public key cryptography has been able to solve for decades (persistent identity, multiple persistent identities) or things you could do anyway ("right now, people can only go to facebook or Google. With Web3, everyone can have their own space!!") because the writer has apparently never heard of a web server.…
But blockchains do introduce a technical capability that never existed before: shared, “trustless” access to and control over data.
Previously, you could run your own webserver, your own email server, etc, and you could trust your own data, but other people collaborating with you would need to trust you to manage that data, and trust that you hadn’t manipulated the data in some way. What if they don’t know you well enough to trust you?
Sure, other people could keep their own copy of that same data, and sync with you somehow, but most pre-blockchain data services lack replication capability out of the box, and as far as I know there are no non-blockchain data services that can give you any assurances at all that data has not been tampered with.
And on top of the issue of trust is the issue of network size. If you personally know who you want to collaborate with, you can share a single server, but what if you want open collaboration and discovery to be part of the application?
Federated application services capable of competing with big tech have been a dream and an objective of open-source advocates for decades, but no one has been able to deliver. I would say the major reason is because trustless data syncing at scale is orders of magnitude harder than running a single standalone server, and all of the solutions until web3 attempted to perform data syncing at the application layer—which means a lot of duplicated effort, and almost zero opportunity for reuse between projects.
Blockchain tech moves replication and tampering protection to the data layer, as a generalized service that is relatively trivial to set up. The promise of web3 is that shared-data applications can be built on top of that data layer in the same way that complex centralized applications can be built on well-defined centralized data layers like the file system and the relational database.
A robust and abstracted data layer allows application developers to spend more time thinking about application logic and less time thinking about data.