Only accessibility-supported ways of using technologies are relied upon to satisfy the success criteria. Any information or functionality that is provided in a way that is not accessibility supported is also available in a way that is accessibility supported. (See Understanding accessibility support.)
What the issue is
Using headings (h1, h2, h3, etc.) improperly by skipping levels in the page structure can make it confusing for users who rely on assistive technologies to navigate web content. For example, moving directly from an h1 to an h3 heading without an intervening h2 disrupts the hierarchical structure of a page.