So, if Google can use Heading 1 as Meta Title in its experiments and meta tag rewrite systems without telling you, we still should care about Heading Tags. Furthermore, Google may use and try new things for Heading Tags in the future without telling you like they stop using Link Rel Prev and Next Tags without telling us for years.
In case your CSS and JS resources can’t be fetched, downloaded, or rendered or Googlebot come to your site without rendering your JS Resources, your HTML document can tell more about your content to the Search Engine.
Google may use Heading Tags in Search Algorithms and increase its value for Search Rankings even without telling you. Do you remember that they have stopped using Pagination Tags without even telling us for years?
Google’s explanation can decrease Publisher’s attention for the Heading Tags, and Google may exactly want this. Because this way, only people who care about a proper Heading Hierarchy can use heading tags in their Semantic HTML.
Imagine that Google makes an explanation for Social Media Shares and Ranking Correlations, we would see a massive explosion in social shares just for Search Engine’s explanation. This is precisely opposite what Google wants. Google wants natural internet interaction without any manipulative intent.