Why is this HTML formatting convention recommended?

[S3RD4R]

I've been looking through a ton of sites recently to get a better understanding of how large websites structure their HTML5 pages.I noticed that they tend to do\[code\]<script src="http://stackoverflow.com/questions/14620506/test.js"></script> instead of <script src="http://stackoverflow.com/questions/14620506/test.js" />\[/code\]but do \[code\]<link rel="stylesheet" href="http://stackoverflow.com/questions/14620506/test.css"/> instead of <link rel="stylesheet" href="http://stackoverflow.com/questions/14620506/test.css"></link>\[/code\]Even in this technique blog they do so, why is this a preferred design style? http://net.tutsplus.com/tutorials/h...5-features-tips-and-techniques-you-must-know/