The problem is that "decentralized" protocols often end up becoming de facto centralized because they lack key economic features.[2] And centralized platforms fill the gaps by offering those economic features — at the cost of giving them total control of the network.[3]
This is why the most innovative and most interesting web applications occur in the browser, which is open and permissionless — and where web domains are mostly decentralized in nature. The only way to ensure a platform retains something close to its original economic properties is to ensure it remains decentralized, but it's hard to resist centralization.
I know HN hates it, but there is a class of protocols that use cryptography and Byzantine fault-tolerant consensus mechanisms and are designed to resist centralization... and they have explicit and verifiable economic properties. They're known as crypto, and involve blockchains. And this appreciation for decentralized-by-design systems is colloquially called web3.
[1]: https://cdixon.org/2018/02/18/why-decentralization-matters
[2]: https://www.youtube.com/watch?v=WGfS6pPJ5jo
[3]: https://knightcolumbia.org/content/protocols-not-platforms-a...