Seems like a common pattern. State of the art models being well replaced by a information retrieval layer (top 10 results) fed into a much lighter model that does something with that plus the original input. Cool result!
Even more than that, I wonder if we could then apply something like this to power some sort of "fact provenance" for the web as a whole, e.g. by populating Wikidata with referenced facts (preferably with extensive human QA).
And systems that allow you to "talk" to a PDF via top results of vector search being added to the prompt are also pretty underwhelming.