I don't mean reusing excel formulas on other platforms.
I mean if you write a really long formula in a cell, it's not really practical to use that formula in another workbook that doesn't have the exact same structure.
If you compare that to say a Jupyter notebook which is cell based, you can at least reuse your function in another notebook or cell within any other jupyter notebook rapidly and quickly if you wrote it correctly. Excel not so much.
You can have named ranges and cells in Excel, and Excel even has lambda/anonymous functions now. So in latest editions of excel functions can be as general or brittle as they are in any other language or environment, it just depends on how they're written.