I`ve been sawing some ICO advertisements since Facebook banned them, so it seems there isn`t a total ban. On the other hand, Facebook can`t forbid you sharing some crypto related info with you friends - that means censorship and to me censorship is against everything that made Facebook become successful. I avoid Facebook campaigns anyway, I think Twitter campaigns are far more efficient (but overall both of them are quite full of spammers and nobody seems to care...).