Its not necessarily true that every coin that is worth it has big trading volumes. There are many projects out there that had the missfortune of coming out in the bear market and suffering from it pricewise. And of course they promote their product, they just dont promote it on guys like us as we are not the products main target group.
It could be that your opinion is correct, but we also cannot deny the fact that with a large trading volume it means that many people are interested in the coin and become one of options to invest. This forum should be one place to promote a crypto project.