Why do you think this can't be verified? You can see the formulas in cells, or you can see the macro code. Further, you could auto import older data inputs and outputs via data connections in Excel and set up some automated checks to flag if something is off.

Is there a use case where you think this wouldn't be possible?

You can verify it sure, but it is much harder to verify excel equations than code. There is no github for Excel (besides saving with different names). You generally don't see the equations when you look at Excel - this is one of the reasons Excel is so error prone.

Fully agree. My point was that it can indeed be verified though in many circumstances.

That said, I think there's always a balance between a quick down and dirty business solution that gets the job done, vs. something fully engineered. Additionally, it is much easier for business users to shoulder more of the workload while letting people with programming knowledge focus on other tasks.

His calculations are usually compared to invoices (ie do the numbers match what we were charged for), other reports and historical data. Similarly when one of our DBAs or BAs creates an important report, we check the results against other data sources.