People are missing the real benefit here entirely.
No one has to go back to corporate social media (and no one should - in my opinion), but Meta's new microblogging platform joining the fediverse means that you can consume content from their users without being on their platform. If even that is too much for you, then by all means, defederate from them, but frankly I don't see the point other than as an ideological protest.
The fact is that fediverse data is already public, and Meta could (and probably is) already "scraping" it (though the word "scraping" doesn't really apply with activity pub) for sale-able data, so the privacy concerns are moot. This change just means more content for the fediverse, more news media posting in a way we can access, and an easier transition for new folks.
Frankly, I see only upsides, though I know that's an unpopular opinion on the fediverse