You're probably aware by now that the Fediverse isn't one website, it's a whole bunch of websites that speak to each other through a common protocol, passing your posts around and processing replies and faves and boosts and all that jazz, and that's what we're talking about when we talk about federation. Each website is owned and operated by Some Random Community-Minded Internet Person. Not a company, just some rando like you, and this rando has final say on what they want on their server.