Heading tags are designed to provide information on the hierarchy of content within a page. Similar to a table of contents, assistive technology users are able to use headings in order to know the main topics a page has and then use the headings to jump to the content they would like to read. Web Content Accessibility Guidelines (WCAG 2.0) look into this further under guideline 1.3.1 , in this guideline techniques such as G141 (Organizing a page using headings) and H42 (Using h1-h6 to identify headings) detail how headings can be used to assist disabled users viewing a webpage.
Additionally, using headings to provide hierarchy to the contents of a webpage also improves SEO by making it easier for search engines and visual users to see how content is organized and what the contents of the webpage is about.
Accessibility (WCAG 2.0 Level A, 1.3.1), SEO
The checkpoint examines the entire HTML source code of a page and reports an error if it does not find at least one <hn> tag (where n=1 to 6). It does not check that the tag is populated with text.