... for this specific use case (financial documents).
These corpora have a high degree of semantic ambiguity among other tricky and difficult to alleviate issues.
Other types of text are far more amenable to RAG and some are large enough that RAG will probably be the best approach for a good while.
For example: maintenance manuals and regulation compendiums.
Why? What if LLMs could parallelize much of their reading and then summarize the findings into a markdown file, eliminating the need for complicated search?