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.
The one thing I would worry about is that a massive deluge of content from Meta would drown out anything else from Lemmy, and would effectively reduce Lemmy to just a client for interacting with Meta. Unless an individual could block Meta specifically (or any one instance) it would effectively kill the All category.
Also would the flood of new traffic make it impossible for individuals to bear the cost of small instances?
That’s just what I think anyway. I’m not totally against federating with them, but very skeptical.