I still believe most activities happens on telegram, even though ads work on targeted users of Facebook. The effect has not been much so far as most now use twitter and CMC ads to promote ICOs.
Yes I also believe that it do not have much effect on the ICOs if they will ban it as people are already sharing their projects on their profiles and on their groups and fan pages on facebook which is playing a vital role for promoting them on facebook. It bring more participants to the ICO when their ICO is promoted via word of mouth on the profiles of people.