It’s not just because it’s meta, it’s because they are going to scrape up all the data they can get (even if it’s just normal fediverse stuff) and pipe it into their data mining operation. They could probably easily do it without us noticing, but if we know they’re doing it… then it’s worth talking about. And reasonable for people to dislike.

Whether they need it to federate or not, it's still reasonable to not want an entity as large and powerful as Meta to consume this data. Fuck Meta because it's Meta, which has a history of being particularly heinous with user data.