The new things people propose as Web 3 use cases, e.g. interoperable game items, simply aren't practical. That's why they don't exist already — not because they require blockchain to build.

I've heard people argue that big tech social media silos will be replaced by decentralized Web 3 social media, but why would they be? We already have decentralized social media. The reason Mastodon can't compete with Twitter isn't because it needs blockchain; it's because Twitter has all the users and all the money, and that's because centralization is just more profitable. It boils down to economics, not technology.