It's a bit surprising to me that Microsoft hasn't created a product that's "you have an Excel file in one of our cloud storage systems, here's a way for you to vibe code and host a web app whose storage is backed entirely by that file, where access control is synced to that file's access, and real-time updates propagate in both directions as if someone were editing it in native Excel on another computer. And you can eject a codebase that you, as the domain expert, can hand to a tech team to build something more broadly applicable for your organization."
Nowhere near the level of complexity that would enter your threat model. But this would be the first, minimal step towards customers building their own tools, and the fact that not even this workflow has entered the zeitgeist is... well, it's not the best news for some of the most bullish projections of AI adoption in businesses large and small.