Google on the one hand prohibits the advertising of ICOs with the excuse of protecting new investors and all others from possible scams, but in reality I think it is one of those "strong powers" that wants to counter the development of the market and the blockchain sector. But despite everything, nobody can stop this revolution
As far as i know about the fact that the majority of scam icos are using the advertisements through the banner to spread the word to all of the audiences around the world.
In fact, I have seen bitconnect, and another Ponzi scheme coin was using advertisement to get more and more victims. It can become a strong reason how those big companies are banning crypto advertisement right now.