Is it worth writing articles that definitely won't rank?

I'm fairly new to SEO, and I'm doing some work on a handful of websites for my company. This includes writing blog content. I've written a few specific ones based off niche search patterns I've noticed, and I've even got a couple to rank on the first page.

The question is, I've heard Google likes regular blog posting (obviously among many other things), and I've written a long, detailed and well researched article about Viagra. The thing is, any keywords around Viagra are incredibly competitive, so I don't have much chance of ranking.

Is it still helpful for SEO? Will Google see it on the site and think "yepp, that's relevant & high quality, this must be a good site!"