Facebook and Instagram are just feeding the users ads from google adsense based on what researches they made , so it'll show cryptocurrencies ads to people that are already invested into the cryptos world and do have a good idea about it , it's not making these cryptos reach new users or anything that might be as much beneficial and rewarding as the money they're paying to spread out their ads ..
Facebook and Instagram users might be kids/aged persons/teenagers with no money or will to invest either their money or minds into such topics and i don't think the cryptocurrencies industry will loose potential customers if cryptos ads get banned from social network platforms .
In matter of fact those social network providers will be loosing all the money they could have got from those ads and they'd better keep them for their own goodness sake .
As for myself i'd be happy for such initiative since i'll not be thinking of cryptos too when browsing my friends or family pictures/profiles and not get an overload of ads that stacks up with those i have already seen in forums .