Originally you could use the schema.org vocabulary with RDFa or Microdata which embed the structured data right at the element. But than can be brittle: Markup structures change, get copy-and-pasted and editing attributes is not really great in CMS. I may not like it aesthetically but embedded JSON-LD makes some sense.

See also this comment above: https://news.ycombinator.com/item?id=41309555