I run a content marketing agency. The problem you're talking about is, indeed, a massive one. But that usually happens when companies create content without thinking about its distribution.
While you certainly must create content that your audience wants to read, it is even more important that you have a clear plan for distributing it. If your content isn't supported by a strong SEO plan, and if you don't have a clear social media and PR strategy for it, you won't see results, no matter how good the content is.
Way more than that. It's a combination of SEO + PR + social media. So you'd have some content that other sites might be willing to publish or link to (say, in a weekly "best of" roundup). Some other content that would focus purely on keywords supported by a backlinking campaign to rank well in search engines. And some other content that would focus on topics that would resonate with, say, the HN crowd.
While you certainly must create content that your audience wants to read, it is even more important that you have a clear plan for distributing it. If your content isn't supported by a strong SEO plan, and if you don't have a clear social media and PR strategy for it, you won't see results, no matter how good the content is.