promoting ICO is very necessary, so that the project objectives can be achieved. usually ICOs are promoted through bounty campaigns, such as signatures, promotions to social media, or youtube ads. it takes more time, energy, and money for that.
I will agree with you on promoting an ICO through bounty campaigns like social media, signatures, but I won't agree with you promoting an ICO through YouTube ads, many people like me use ads blocker and other don't listen to the ads when they appear, they will cancel it immediately, YouTube ads is not a good way, it will be a waste of resources.