For ICOs, it's all about marketing, I look at coinmarketcap.com and I have trouble finding something with real substance.
For cryptocurrencies in general, we have to be fair and give some merit for alts like Litecoin and Monero.
Is there a proof if the ico is all about the marketing, i think that you are wrong in this moment, But honestly the marketing give very big impact to the project to promote its own project but the main reason still on the idea and the development process, if the development process goes smoothly and that will attract a lot of the investors, and i don't think that the marketing had all of the role in this game.