[FormFollowsFunc]

I remember they had something similar 15 years ago. It was called tagged PDFs. It was useful on low resolution devices like PocketPC as the full page view wasn't readable. You had to convert your PDFs before loading them onto the device. Probably went out of favour when the iPhone came along and screen resolution increased. Looks like it’s an upgraded version of this with added ML.

[Finnucane]

Tagged pdfs are still a thing for accessibility, to make pdfs work better with assistive technology. In practice, this is underutilized, because of the additional effort to use it properly.