[player2121]

There are plenty of apps out there where you cannot apply HTML document semantics or that would be a waste of time (money) doing so.

If using canvas or web-assembly would be easier/possible than using HTML tags for a rendering layer, nobody would ever disturb the HTML document designers with this div "soup" :)

Semantic HTML serves 2 purposes: lets search engines correctly index your content and makes it easier for a human to edit this HTML directly. Other than that, there is no other reason which requires semantic HTML.

True accessibility is achieved through other means.