Using punctuation correctly is important regardless of your occupation. If you are a blogger that is even more important; most readers consider the quality of writing determinant for the success of a blog.
Stephen Covey is one of my favorite authors. In the book “First Things First” he describes a story that one of his associates experienced on a seminar. In the middle of the lecture the presenter pulled out a wide-mouth jar and placed it on the table, aside to some fist-sized rocks.