while I agree they are probably doing this and we should have better data privacy/ownership, the scope of the data they can pull from the fediverse is substantially less than what they get from their platform.
when you’re on Facebook, they control and track everything. which posts you see, which you don’t, and in what order, how long you looked at a given post, whether or not you scrolled through comments, every movement of your mouse, everything you typed and deleted in that text box, where on the screen you touched while you dragged to scroll, what text you highlighted, absolutely everything.
the only data they can probably pull from the fediverse is posts, comments, and like/dislike. maybe which posts you clicked into if that’s public and I’m pretty sure they can’t get which posts were shown to you without owning the instance you’re on.