My personal account got banned a couple days ago, I thought it was weird since I just wanted the referral fees off the platforms. It had nice conversions, wasn't breaking any of the rules they put out - the copyrights, the images allowed, etc.
I can see why they wanted to ban ICO's, since some of them don't look super promising, and other coins are being founded for the sole purpose of raising money. Most of the sub-200 coins don't even need blockchain technology, and just slap on words to make their whitepaper 50+ pages. I understand how Facebook sees these coins as not acting in good faith. I can see how they want to protect their users.
ICO's by definition, encourage others to invest in them, just like crowdfunds. I bet what's happening is that through the rise and fall of December/January, Facebook is getting a lot of reports that this crypto thingy is a huge scam. Some ICO's have disappeared entirely, like Confido, and there are plenty more on deadcoins.com, a site I stumbled upon while googling coins that failed.
Facebook is taking this initiative right now so that I'm guessing their team can learn more about crypto, and then they're going to narrow down which ones are real scams or not. This could something to look out in the future, as it might be good for the coin (publicity/advertising advantages on Facebook) as well as their belief in the strength of that crypto coin.
Upon further reading, I found out Facebook's official wording/statement on crypto:
Ads must not promote financial products and services that are frequently associated with misleading or deceptive promotional practices, such as binary options, initial coin offerings, or cryptocurrency.
So no more advertising for referall fees, no more publicizing your cryptocurrency's facebook page/following/group. Guess what? Instagram and Google Ads are still open! Also, the ban is only on ads, so you can still grow a page, and then post an article on there, so that it's not an ad. Hopefully your audience engagement rate is big enough :)
Good luck in the advertising space!