You're right. No matter how promising the crypto project may be, but without strong marketing it will not survive. Even such a promising project as IEX needs marketing support.
Absolutely all projects need advertising and marketing support. Do you think that the projects from the top 10 CoinMarketCaps are not spent on advertising? You are mistaken. So just a huge cost of marketing support. Project IEX is conquering the market for itself. The guys do not have such budgets for advertising. Therefore, project IEX is gaining popularity among users only because of its unique technical ideas and solutions.