Google never had a problem working with content that was blended with it's visual presentation. They literally doesn't care. They crawl anything even pdf and other non-html content.
The semantic web was born from a belief that it would enable a peer to peer web that never materialized. Accessibility was better solved by aria annotations a long time ago and the semantic web was never going to properly solve it.
FWIW, it's hard for a peer to peer web to materialize, where the web is almost entirely built and funded by entities who very much don't want a peer to peer web, and in fact actively fight it.
The semantic web was born from a belief that it would enable a peer to peer web that never materialized. Accessibility was better solved by aria annotations a long time ago and the semantic web was never going to properly solve it.