Most of English instance are using Misskey-fork named Sharkey.

Misskey itself has tons of unique features that Mastodon don’t have, like threaded discussion/reply, Misskey games (only two for now), custom interface, emoji reaction like Discord/Slack.

Misskey?

They did.

There’s almost hundreds of dead social media that inaccessible, some even have zero backups. https://en.wikipedia.org/wiki/List_of_defunct_social_networking_services

Some content are just cached on other server, but not all data like credentials or full content.

I don’t think Lemmy dev even have the opinion you stated above…