This is all due to fraudulent ICOs. At current time 9 out of 10 ICOs are total scam. They do a fundraising and spend nothing on anything except for roaming around and spending in useless things. And it's a good move from social sites to block those ads until we have regulations of the ICOs.
Very true that these scam ICO did contribute of this banning but i think this move will also will favor the legit ICO in which this time they will ask the ICO of legal documents during acquiring their advertising services in which all of the fake ICO for sure cannot comply. Soon we can truly participate and join a legal projects without hesitation as this famous sites main objectives is the good welfare of their billions of users.