It is a known thing that Facebook pushes the envelope by asking individual account holders to promote their personal statuses in order to gain more visibility. The issue is more poignant if you are a Facebook page admin.
Here Derek Mueller, from Veritasium, explains how Facebook takes your money to bring you more likes, likes of which many are fake, and then hides some of your content in order to make you buy more likes.
It seems that Facebook is not hiring click farms, but instead guys from click farms simply clickthrough and like many pages in order to hide their false likes under a rain of seemingly natural likes.
Facebook knows this, but it won’t let you delete/block such fans in bulk. In return you get many fans, low engagement and even lower exposure. Well done, Facebook!