Great questions, Joe.
So first, I need to address a common misconception — it’s just as easy to build these visuals in Excel as any other data viz tool. People just aren’t aware of the features.
There are so many use cases for an Excel-focused design, and I will be writing more about these but you hit the nail on the head for the first one- if you want a design that is dynamically tied to your data, it’s a great solution.
Another big factor is internal security requirements: a lot of enterprise companies limit the software you can use internally but almost all of them let you use Excel.
One that I deal with very frequently are clients trying to get approval/funding for a dashboard or data visualization project and need to a proof-of-concept. Excel is typically the quickest and easiest way to use real data to build a dashboard prototype.
Those are just a few. But there are so many more. It’s a surprisingly capable tool and is often the best option for people doing data-focused designs.