That's not necessarily true. Getting content marketing articles up on the front page of big news sites (like Hacker News) can be an important spark to longer term sales. Once your article hits one big site, the other bigs sites tend to pick it up and you see lots of viral spread on Twitter. If viewership is wide enough and your product worthwhile this can be a big enough spark to initiate organic word-of-mouth marketing. In addition all this aggregation of your content drives increased link ranking back to your site, which improves SEO. That last part works better if the article is hosted on your own domain, though.
Source: I recently finished researching a ton of successful startups to determine what common factors they share (and wrote an article with all the data and analysis).
