terrible title, this post actually explains how to use Haml the plugin to generate all sorts of content using its existing features like filters properly. The confusion is that "Haml" refers to Haml the plug-in as well as Haml the syntax for generating HTML. The syntax is not ideal for content, and that's why it supports things like inline HTML and markdown filters, just as the outline explains.
the only thing it's really ideal for is software engineers writing their own HTML. in professional team environments in my experience designers always like to be able to at least dip in to HTML, and as "illogical" as this might seem to a programmer, they are <i>never</i> going to learn something like HAML - it's just too complex and programmery.