I don’t think we should take this article at face value. Putting a heading <h2> inside the <summary> is weird and the aforementioned article recommends against it (most experienced web devs know not to put headings inside interactive elements other then <a>).

On top of that we have people in this threat that use screen readers and claim that they have no problems with <details>/<summary> which aren’t present in other elements[1].

1: https://news.ycombinator.com/item?id=34547915