Given the 6 hours time constraint, I believe the test applies the breadth of content more effectively than anything one may do with Excel. An LBO model, for instance, falls very short of the breadth of the CFAI content, and it would take considerable time on the exam.
The certifications provided by Wall Street Prep and Breaking into Wall Street already do something very close to what you suggested. Some employers may even prefer those - others may see it as a nice add-on.
The appeal of the CFA program is that charterholders are disciplined and have had some basic education on all the main finance topics. Even when they’re rusty, you know you can hire a charterholder and she or he will likely get up to speed quickly on any topic.
Of course, any topic would be better to learn than how improper it is to use CFA as a noun.