Because they believe that Facebook prohibits bitcoin and ICos and other cryptocurrency
The new Facebook policy will not allow announcements of known digital currency exchanges or initial offers of currencies.
Is it to avoid fraud or false advertising? That's why?
You arent reading ,based on facebook terms and conditions they will not accept any ICO related advetisement to their paid advertising program to eliminate scammy ICOs in facebook community.It doesnt mean that they will ban your account if you posted,share and link any ICO related topics using your profile the only affected by this restrictions woauld be the people who are paying facebook for their ICO advetisements.