The ad supported is just the reason to make it addictive. Get rid of all likes/thumbs/follower(counts)/notifications and it loses the endorphins and stops being the problem it is today.
Hey you spent 500ms looking at this pretty girl dancing, how about some ass now?
I get straight up PORN ads on Facebook too. Twitter at some point showed me porn as well, even if I had specifically curated it to show JavaScript content.