I don't think anything you're saying is untrue, but I do think you're ignoring how shady and unethical Facebook is when they feel like it. For example, they do

I don't think anything you're saying is untrue, but I do think you're ignoring how shady and unethical Facebook is when they feel like it. For example, they downgrade YouTube videos in people's feeds. There's no reason for that if they have a better product.