I agree with almost every comment in this thread, except that few seem to appreciate that "It should be one big fediverse, which instance I use should be completely transparent and irrelevant." is impossible without decentralized permissionless consensus: yes, blockchains. This is the thing they've been calling "web3", as much as HN seems to hate it.

web1 -> peer-to-peer decentralized networks without built-in consensus or economics; end up de facto centralized; SMTP, Nostr, RSS, etc.

web2 -> corporate owned networks; from iMessage to Tiktok to Reddit, this is most major networks today

web3 -> networks whose decentralization is enforced by cryptography and economics; Ethereum being one such example of a programmable network/computer

If you don't have cryptographic and economic mechanisms to encourage decentralization and resist centralization, we will just end up with a federated/fragmented system or a centralized one. We will keep repeating this loop over and over again until we fully appreciate that networks need built-in economics or someone else will build it and control them (see git/Github; RSS/Twitter; SMTP/Gmail; many others).