I've been given this markup structure as a recommendation from a SEO agency, about the way to best use html Headers for SEO purposes:<h2>{{section-title}}</h2><div class=carousel>    <div class=carousel-item>        <h4>{{category-name}}</h4>        <H3>{{category-title/desc}}</h3>        <a href={{url}}>{{link-to-category-page}}</a>    </div>    <div class=carousel-item>        <h4>{{category-name}}</h4>        <H3>{{category-title/desc}}</h3>        <a href={{url}}>{{link-to-category-page}}</a>    </div></div>It screams not right all the way to me, first of all broken hierarchy (h2 then h4 then h3), no content after h2 and h4 headers. I can see the negative implications in terms of accessibility (e.g. navigation), unfortunately this is not a priority for the client.Are there any benefits for real, that are eluding me, with such markup in terms of SEO?
Html headers structure for SEO without content and broken hierarchy
seo;html;headers
What your SEO agency is doing won't make a lick of difference for SEO.  Adding heading tags was an SEO strategy that maybe worked five years ago.   Today Google uses signals other than heading markup to know what text is important an the page.  Googlebot actually renders pages.   I've seen SEO testing that indicates that Googlebot now views any text that is big, bold, and prominent as important.  It doesn't matter if your site even has heading tags.   Styling a bit of text with CSS will have the same effect.On the other hand, added heading tags won't hurt in any way.   Google has never paid any attention to proper use of headings as a ranking signal.   As far as Google is concerned, there is no requirement that headings have content.  There is no requirement that headings be in the proper order.   There is no requirement that headings convey any sort of semantic meaning.    Your rankings will not change in the slightest having these tags added.It also turns out that users don't care about the tags you use.   They only care about what they see on the page.   It just isn't worth getting upset about this.   Maybe other than that the SEO agency should be doing something more productive and not wasting time.