I think the core challenge here is that being able to (in "development") quickly change the prompt or other parameters and re-run the system to see how it changes is really valuable for making a tight iteration loop.

It's annoying/difficult in practice if this is strictly in code. I don't think a database is necessarily the way to go, but it's just a common pattern I see. And I really strongly believe this is more of a need for a "development time override" than the primary way to deploy to production, to be clear.