I bet this Excel Feature has been another TOTALLY IGNORED Customer Demand for over 30 years.
I know it has been for me and the new music scale that I am working on the requires 64-digit significant digits JUST FOR MY PROTOTYPE, then I REQUIRE 1024-digit significant digit math precision.
Some Math Theorist Can Get 2^31-digit Signification Digit Math Precision from Excel using the SD version of the xlPrecisionCalc Excel Add-On. BUT IT ONLY WORKS WITH EXCEL 2016 AND EARLIER, NOT 365 AT ALL!
DUE DILIGENCE WENT AND MADE ME CONTACT BOTH VENDORS TO GET THEM HOOKED-UP.
THIS IS THE ABSOLUTE MOST EGREGIOUS ASPECT AND MOST EDUCATIONALLY DEPRIVING STOOPIDITY OF YOUR <BLEEP>ING <BLEEP> SOCIAL ENGINEERING BS, EVER!!!
I still have not heard back from Microsoft Excel Owner/Manager yet, and I have now gotten so fed-up with this MAJOR DESIGN FLAW, not feature request.
If my simple music scale BREAKS EXCEL MATH, who else's stuff is broken due to REALLY INSANE, bordering on SOCIAL ENGINEERIN CONTROL-FREAKS DIS-ALLOW THE POPULACE FROM SEEING WHAT IS BEYOND STUPID 13-DIGIT MATH PRCISION.
S T O O P I D ! ! !
JUST GIVE US 1024-DIGIT MATH PRECISION AND CHAND EXTRA ONLY FOR THOS THAT NEED MORE THAN THAT!!!
Actually what you suggest is to re-build Excel from the scratch and create totally new product, perhaps with old interface as functions names (but in background, form calculation engine point of view, that will be new functions). Same will be for any other (okay, at least for majority of them) spreadsheet product as Google Sheets. Microsoft is rich enough company, but I don't think they have enough resources to invest in such project, plus return of investments is unclear.
As for xlPrecisionCalc that's third party tool, that's its authors decision do they like and do they have enough resources to support the tool for modern Excel or they stopped with it. That's usual issue with any third-party tool, you never know will it be supported or not.