From your OP description:

EDIT: the AI creates an initial description, which then receives crowdsourced additional context per-image to improve generated output. look for the “Example Output” heading in the article.

That’s wrong. There is nothing crowd sourced. What you read in the article is that when you add an image in the PDF editor it can generate an alt text for the image, and you as a user validate and confirm it. That’s still local PDF editing though.