Comments with No Content

I've worked with HTML, CSS, and JavaScript for a long time, most often using Dreamweaver in my capacity as a technical writer. In all my years of embracing these technologies, I've looked at hundreds of web pages and, likely, at least 75 out of 100 times, I look at the source code of the web page I'm viewing - I geek out that way. I fully realize that I have not seen every web page on the Internet - no one has. Therefore, what I'm about to highlight may be a standard practice, used in each of the web pages I've never seen. However, I have my doubt all of those pages utilize 'empty comment' tags as a best practice: