Have you actually configured agentic AI-driven DM? My experience with LLMs tells me that thay are not that good at following large amount of rules/instructions, especially custom ones. At least that's my experience for reasonably sized self-run llms. And a DnD game involves thousands of pages of various manuals + the campaign itself. Kinda doubtful you can do it reliably enough. Mechanizing it with explicit software should be a more sure way to do it.