Lately, I’ve worked on two CMS platforms which added empty paragraphs, i.e., <p></p>, as carriage-return line breaks when using their HTML editor(s).
Example:
<p>TEXT</p>
<p></p>
<p></p>
<p>TEXT</p>
Movable Type has a similar method for the markup of comments with its “Paragraphs and line breaks are automatic” feature.
Example:
<p>TEXT</p>
[Program-generated Space]
<p></p>
[Space]
<p></p>
[Space]
<p>TEXT</p>