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.
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.
Well we don't know what those features are yet, otherwise people would already be trying to implement them! It could be anything though, maybe the servers are just much faster, maybe the UI is more slick, maybe they're the first to implement a load of the features we like from RES, maybe they sell you some extra content for that vendor lock-in. Whatever it is, if they implement it in an unfriendly and/or incompatible way, they start a schism with the rest of the Fediverse; if they're sneaky and wait until they've already got their claws in before doing this then they take a chunk of the more casual users with them.
All this isn't guaranteed to happen, but it seems relatively likely and therefore something people should be prepared to deal with!