Hype comes mostly from the fact that people are icentivized to share it trough comissions over purchases by referrals aswell as that everyone hopes that more people = more profit.
But advertising and marketing is important, there are allot of projects that are fantastic (afterschool for example) but fail because there's a lack of exposure. Afterschool did something about it though and they're ICO is a succes now. It is a solid project with a committed team that really wants to mean something out of their own experience in the industry they're involved.
Advertisement is HUGELY important you have no idea how much this affects people. Everyone loves McDonalds right? And thinks Mcdonalds is great? They still advertise.. they want you to think of them else burgerking would appear everywhere and people forget about McD. People also expect commercials.
Netflix is huge aswell but they sure do advertise. Coca Cola is great, they advertise. I can go on and on..