Blog commenting is also one of the fastest ways in building site reputation. It is the quickest methods of Search Engine Optimization. Blog commenting involves just reading an article and giving it a related comment and when the blog owner approves your comment, or better if the blog is unmoderated, your comments are giving you traffic in a snap.
However, there are still some disadvantages in blog commenting. It might be a quick way to get backlinks, but is should not be abused at all cost. Your search engine optimization efforts will be wasted once the blog owner marks your comment as spam. Posting senseless comments should be strictly prohibited. If you're posting comments that are unrelated and out of hand, you are just risking the rankings of your site.
And moreover, some blogging platforms like wordpress sometimes ban IP address so take extra care in placing your ideas on the web.