HN is not as open as other group sites like, say, reddit where it's up to the users to decide what's important. It's run with a specific purpose of quality of stories within a specific set of topics and a vehicle for promotion of YC-related content. Voting exists to provide group input within those guidelines.

The bit about writing a blog post and submitting it is out-of-date based on current mod behavior. If you want to provide commentary, post the original source and add a comment. Links to blogs are nearly always pulled for the original source unless the blog is the original source on an overall trend, research, etc.