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’ll give you an ELI5 answer:
Have you ever been playing with your same age friends and then a bunch of older kids come by and ask to join? You say yes and then they take over the field and ball and start playing the game they want and dominate the play. Pretty soon it’s the older kids’ game and you’re sitting on the sidelines.