I'm pretty sure they don't. Zuck's no fool.

the 'scam scenario' might have just been an impetus leading to the decision. though as stated in part one - how many ads have you seen for the QUALITY blockchain projects on Facebook? Probably zero. The good stuff doesn't need marketing channels like Facebook's. Thus, there's no real damage done to the players with integrity - as if they're really strong enough and have the substance, network effects alone will do way beyond what marketing campaigns alone could.