Google’s John Mueller discussed heading elements with a member of the SEO community where he affirmed the usefulness of using hierarchical structure when using heading elements. “h1–h6 elements have a ...

The belief here is that the keywords you use in H2-H6 subheadings are more heavily weighted in Google’s algorithm than words in plain text and that tags are therefore a ranking factor of their own.

Gary Illyes from Google said that the HTML structure for your web pages does not matter much for rankings. He said this on the latest Search Off The Record podcast, saying, "I know that some people ...