The arguments I've heard about tracking etc are misguided and don't understand the actual risks.
Firstly, posts on the fediverse are already likely being consumed by advertising platforms like Facebook & Google. It would be trivial for big tech companies to setup relays that act as scrapers.
Secondly, the value in platform's tracking individuals is for advertising. There is no mechanism for these platforms to identify you browsing the we if your instance federated with threads. Your instance won't share cookie sessions etc with threads. It doesn't increase your exposure.
Thirdly, these platforms have the know how to deal with spam and they will be incentivised to share that tech with other federated instances.
Don't get me wrong, Facebook is an evil company. But I haven't heard a decent argument as to why them joining the fediverse is a bad thing. We always have the option to defederate in the future.
Change my mind.
I've been around long enough to see many projects be extinguished.
To your first point, these companies essentially have infinite money compared to you, me, everyone combined on Mastodon. They can and will figure out a way to track you across servers and they will figure out how to exploit that. Cookies weren't supposed to be used for tracking they way they are, but the money hoarders figured out how to exploit them. Browser fingerprinting wasn't a thing, but it can now be used to track you. How you type and how you speak online can be used to ID you.
If you think that Facebook is willing to share anything, I just don't agree. Facebook will create Threads, they'll put it on the Fediverse, they'll align, then eventually they'll start building features that Mastodon, Lemmy, etc refuse to or literally can't or won't have the time to do, and then they'll start selling how they're so much better and you should come join them, or they'll say they're more secure, or they'll just smear the others. People will flock to the new and better, because hey it's still on the Fediverse and open, eventually they'll close it off and strangle the life out of the Fediverse. I'll still be on the Fediverse, but these platforms are all about content. If people stop showing up, they can still exist, but they're basically useless. It's happened before, it'll happen again.
Facebook has open sourced loads of their internal tools, for instance PrestoDB. Open sourcing their internal tools is an advantage for Facebook as they get contributions from other developers. Fediverse tooling would fit this model.
Facebook will do what's best for Facebook. If Facebook joins the Fediverse then sharing tools to reduce spam will benefit Facebook. So I predict that Facebook would share such tooling.
I don't understand this argument. Who do you think would be lured from Mastodon to Facebook Threads? Is there a feature that Facebook could introduce that would make you consider moving to Facebook? I can't think of one.
They already do this though, it's called Facebook, Twitter, Instagram, etc. That's why the EEE argument doesn't make sense. The distinguishing features people keep talking about already exisit in a wall garden yet Mastodon has users. The features that Mastodon users want is freedom and control. Threads can't compete with that but Threads can introduce millions of users to the concept of federation.