Afaik, whenever an Activitypub instance has defederated from another it has always had to do with some combination of bad user behavior, poor moderation, and/or spam. Are the various instance admins who have decided to preemptively block threads.net simply convinced that these traits will be inevitable with it? Is it more of a symbolic move, because we all hate Meta? Or is the idea to just maintain a barrier (albeit a porous one) between us and the part of the Internet inhabited by our chuddy relatives?
(For my part, I’m working on setting up my own Lemmy and/or Pixelfed instance(s) and I do not currently intend to defederate.)
I would add as most important: psychologically unhealthy behaviour their algorithms are promoting.
It starts normally, but algorithm is rewording unhealthy posts and soon whole network is full of it, it happens since they are just hunting “engagement”, click, time in the app and basically addiction.
The Algorithm only happens in their app, though. They aren’t forcing it on every Mastodon server, and definitely not on anything Lemmy.
And, yes, The Algorithm is truly awful.