The most successful ICOs in the past did not rely on Google Youtube or Twitter advertising. Ever heard of influencer marketing? They take on people with huge networks, make them either ambassadors of their projects or get them to write about the project or make videos about it. That sort of advertising is not banned, as it is not unsolicited. These guys have a lot of followers and they tend to trust them about the projects they talk about. Much more effective than direct advertising that no one clicks on in fact.