Because then someone with a business school education (and zero formal statistical training) wouldn't be able to do it. I joke about waiting for finance's Excel models to be rebranded as AI, as I've already seen a handful of hedge funds rebrand their analysts as data scientists.
To be clear, my original comment was not criticizing Excel. It pokes fun at analysts who couldn't tell you a Type I error from a Type II being branded as "data analysts" because they build DCF models.
Certainly it has good features to create what you want, and you could edit source (if you can read it!)...but it's used by people who have a elementary knowledge of web development.
Maybe I'm being a curmudgeon. In my book if you can't build the statistical tool you're using, you don't understand it. So if, in Excel, you can fit a regression from "scratch", (i.e. not using any built-in regression functions) and use the built-in functions for convenience, that's fine. If you can't, you're a regular financial analyst. (Nothing wrong with that. I was one once.)
This is important because being able to build it means being able to tweak it. Excel's tools have quirks and make built-in assumptions about your data. If those assumptions don't hold, you should be able to tweak (or change) your approach. Being limited to built-in models removes that flexibility. It also implies you don't know when you're crossing between "my tool works" and "my tool is outputting garbage."
For work to be "science", it really ought to be transparent and reproducible within your community (eg, team within your firm).
Here is a summary of the story: https://www.nytimes.com/2013/04/19/opinion/krugman-the-excel...
I suppose it depends on what you mean by "can". Much like whiteboard interviewing, I bet I can't sit down today and implement a regression from scratch, because I'm out of practice. I have had no need to retain that information; there are tools that do it for me.
Could I do it quickly with a stats 101 textbook in my lap (or 10 minutes of Googling)? Absolutely.
This is absolute pure silliness. So the guy down the street that can't manufacture a new carburetor isn't a mechanic? The doctor that can't create penicillin in his personal office isn't a medical professional?
More often than not, the people that create new systems are not the same people that take these concepts and apply them to practical business problem. It takes many kinds of people to help a company grow.