Obviously they can adjust their fee up or down to further their interests. Obviously they have the right to set the 'floor' auction price, and can set it to maximize profits. Obviously they can take on business from Facebook, and limit how much they take on if they like.
It doesn't include stuff about their recent switch to first price auctions, which make many of these complaints moot. It's really hard to make a first price auction unfair.
Why was any of this a surprise?