Would blockchain work better for the Fediverse, instead of Email Style Instances?

Nope! The main thing going for a distributed ledger would be global consistency, but there are some very negative downsides. It's slow, scales poorly, puts a massive burden on admins operating instances, and the blocks would be effectively immutable...meaning that if the contents of each activity were fully nested inside of a block, edits or deletions would be impossible. We already see problems with CSAM showing up in various blockchains, and a Fediverse blockchain used for social purposes would be no different.

It's just not the right tool for the job when it comes to social networks. There were a few early experiments in this area, such as Twister, which tried to build a Twitter clone on top of a blockchain using DHT. It has a huge list of limitations, though, and development stopped around 2020.

No.

To have a decentralised network, you need a lot of servers storing some data and a access algorithm thar searches for the pieces. There are a lot of hard problems:

• you need various copies because each node can go offline any moment. This works for pirated DVDs, but not for social media posts.
• you need to store a lot of the network in each node. The user needs to contribute to the network. Few people will donate GBs of storage and bandwidth to use a social network. You will get only a few enthusiasts.
• search is a nightmare nobody have really solved.

The architecture is good for storing and distributing many copies of a few very popular contents (and shines in torrent) but is bad for storing, searching for, and accessing many unpopular and mildly popular contents.

Better how?

Can I ask what you're planning to use block chain for? To verify each account? Or to federate instances?

The blockchain is always a scam.

I'm totally in favor of a fully distributed solution! But you don't need a ledger for it, neither centralized nor distributed. A simple pub-sub + DHT, torrent style, should be enough.

Blockchain is the wrong solution for that problem.

Check out Nostr, its's pretty much what we need.

Blockchain does not mean decentralized. There are completely centralized blockchains, and there are completely decentralized systems without blockchains (like Tor).

Centralization is as much a human problem as it is technical, that's why everyone joins mastodon.social instead of looking for a smaller instance or spinning up their own.

As for a more decentralized Fediverse, I think https://holos.social/ is a super interesting idea.