Excel is great at providing a mediocre database, presentation template, calculation engine, and model builder, all-in-one. It's even Turing complete (although it makes it hard to write decent code, since that's not the point.) It does a large number of things, and a mediocre job of all. Often, this is enough. It gets the job done for small toy problems, and often that's a start. However, basing billion-dollar decisions based on Excel code? Are you kidding me?
This is exactly why I rail so hard (and without giving, ever) against Corporate injections into software. Corporate America is founded on mediocrity being good enough. Sometimes it is. Sometimes, it's fucking not. When it's not, stop using Excel as a database (it's not one) and fire all your CommodityJavaDevelopers writing SingletonVisitorFactories and start doing things right. Since you don't know how, you have to hire someone like me and give that person lots of autonomy, but it can be done.