Your RAG can't answer 'why' -- GraphRAG finds what vector search misses

The question that broke my RAG pipeline I had a solid RAG setup. Embeddings, vector store, top-k retrieval, the whole thing. It handled factual lookups just fine: "What's the API rate limit?" "Which config file controls logging?" Quick, accurate, done. Then a teammate asked: "What technical challenges do Project A and Project B have in common?" The system returned chunks about Project A. Chunks about Project B. Individually relevant. But it never connected the dots between them. It couldn't, bec