Because thats how the world works. People lie and studies shown that big corporations act like psychopaths. You will never get rid of this thing. Also, everyone in the whole world can just read your content off every fediverse server your server federates to, manually or through scraping. It literally is a nonissue if they made an undercover instance because they can read it everywhere.
But that is also the idea. If your message can be gotten everywhere, nobody can artificially ransom them for money (looking at you, reddit, stack overflow, facebook, twitter, etc).
This fact is rarely discussed but a major factor why the fediverse helps with democratization of the internet. Free information.