If meta wants to harvest data they would just create boring no-name servers to pull down the data that they want. De-federation isn't going to stop that.
The goal isn't to create a system where there are no corporate instances. The goal is to create a network that doesn't rely on corporate instances.
This idea that we use use de-federation like a weapon will cause the Fediverse to fragment and then we're back where we started: 50 different social media services and a fragmented social media experience. De-federation isn't a super downvote button, its use should be limited to boring server-related things (spam, complying with laws, etc).
The strength of federated social media is that it is all available for everyone at all times via one account. Breaking the network into small chunks or having some central group decide who gets to have access to social media is the exact thing that the ActivityPub protocol is suppose to help people escape from.