Topic tags are not hand-curated. Various algorithms are recognizing certain keywords and tagging articles on the general subject. It is not always "smart enough" to recognize tone or viewpoint.
For example, a topic like #Health Care Law can contain articles for or against policies, as well as different related news and stories. It's a great way to to see a wide variety of content on a topic.
If you are looking for more content from a specific viewpoint on a topic, we would suggest following user-curated magazines or other sources.