While I understand the sentiment, I'm not sure how bash could ever be as maintainable as a something written in e.g. Python (or even better, a strongly-typed language).

The thing with bash is, it's great for tying things together and quick bits and pieces, but it's not set up for writing maintainable code. Arrays, functions, even if statements comparisons can all be done in bash (as first-class features), but are just... easier in other languages. And then think about the refactoring, linting, testing tools available in bash vs other languages. And then on top of that, there's the issue of handling non-zero return codes from programs you call; do you `set -e`, and exit on any non-zero return code even if you wanted to continue, or not `set -e`, ignoring any errors as your script just continues.

Personally, when I feel I want to use a function (or array, or other similar, non-trivial thing), in bash, it's time to reach for another language.

Having said that, there are some nice programs written in bash. https://www.passwordstore.org/ being one that comes to mind.