The "non-programmers" part was the earth-shattering change; before that managers had to ask analysts to do the work or setup the program for that particular question; 1-2-3 let them build it out themselves and play with it before showing it to anyone.
I've been implementing the functions Lotus 1-2-3 made mainstream as a REST API — amortization, NPV, IRR, compound interest — and the formulas are completely unchanged from 1983. Forty years of software evolution and the computation at the bottom has been stable the entire time.
What changed is only the interface layer: mainframe COBOL → Lotus cells → Excel formulas → Python libraries → REST endpoints. The spreadsheet era was the step that made financial math legible to non-programmers. Everything since has just been a different packaging of the same numbers.