Everywhere I look there are people advocating for defederation from this and that! Do you even understand what you're suggesting? Do you get what's the point of decentralized social media and activity pub?
This is supposed to be free and accessible for everyone. We all have brains and can decide who to interact with.
If meta or any other company manages to create a better product it's just natural that people tend to use it. I won't use it, you may not use it and it's totally fine! It's about having options. Also as Mastodon's CEO pointed out there's no privacy concern, everything stays on your instance.
Edit: after reading and responding to many comments, I should point out that I'm not against defederation in general. It's a great feature if used properly. Problem is General Instances with open sign-ups and tens of thousands of users making decisions on par of users and deciding what they can and can not see.
If you have a niche or small community with shared and agreed upon values, defederating can be great. But I believe individual users are intelligent enough to choose.
Defederating "from this and that" is actually sometimes problematic here. It's about instance admins finding balance between freedom and usability (limiting spam and hate). Beehaw.org defederated from lemmy.world and sh.itjust.works, lemmy.world defederated from exploding-heads.com etc. These decisions were controversial, but they weren't bold. On the contrary, much thought and care went into these and that can be seen in communities' support for them (in case of Beehaw, along with hopeful awaiting of refederation by users and admins alike).
But that seems not to be the main issue you're presenting. Defederating from Threads specifically is an entirely different matter. And people who advocate for it, including myself, have more arguments for it than just privacy.
Though it's not the main point of my comment, I'm gonna list some such arguments, simply to back my words.
The EEE. Meta could (and quite probably will) try to federate with its millions of users, then use extended protocols putting pressure on Fediverse to adapt, in order to satisfy Meta's users. They can make it difficult to keep up (e.g. by providing purposely flawed documentation) and the users will grow tired of stuff not working here but working there. Once users register with Meta (since it's a part of the Fediverse after all, right?), they'll cut the rest of us loose.
Badly moderated content. Facebook is already full of it.
Meta has a history of terrible actions and should not be supported.
Thanks for this great comment! Yes, I totally agree with your arguments and personally hate meta. My problem is posts like this and misinformation about underlying tech (like privacy and ads). Meta will do anything to be the sole winner, but as I've pointed here it's a dilemma and defederating can actually encourage more users to stop using Fediverse to begin with!