Facebook runs on one simple principle: "What's Good for Zuck is Good for Zuck." More yacht-feet. More... actually, I've no idea what he actually cares about, beyond more ZuckBucks.
Everything else is secondary to, and subservient to that. Big conspiracy? "We are so, so sorry that you caught us doing that, because if you think we're evil, you might view fewer ads by spending less time engaged in the site. We promise to tell you that we're going to do the work to learn how to get caught less often doing that thing you found us doing."
Facebook isn't your friend. They're not your companion in your quest to... whatever. They are purely interested in how much money you can bring them, either directly through ad spend, or indirectly through being super engaging such that other people spend more time on Facebook viewing ads. Anything else you think of them is simply wrong.