What use is this?

XPath is used extensively in XSLT to process and transform XML documents:

<xsl:transform version='1.0' 
               xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:template match="/">
<html>
<head><xsl:apply-templates select="doc/title"/></head>
<body>
<xsl:apply-templates select="doc/contents"/>
</body>
</html>
</xsl:template>

</xsl:transform>

XML Schema and other standards use this for similar matching needs.
Many programming APIs & commercial products provide XPath for traversing and manipulating XML.