Why Text to SQL not going to work

Just want to see hackers response about text to sql and RAG. It is promising to generate SQL using GPT4 and run for small databases but it completely fails with databases with hundreds of tables. GPT doesn't know how to generate complex queries even with enough metadata. This is my problem, copilot like enterprise chatbots with RAG is hard to build to get 90% - 95 accuracy Any solutions ?