I don't think it is action taken to reduce the scams because still anyone can post on facebook about the ICO or the crypto currencies.I think the facebook community want to retain their reputation among the people by not doing their paid promotion because many projects are turned into scams.
So it is not an effort to stop the scam ICOs they just want to stop getting involved any kind of scam project promotion.If they really want to stop the scams they completely have to ban any ads about crypto even by the users.