Other than bash not being portable to even the exact same machine, due to having so many footguns. Creating a new file can potentially fail a previously working bash, because it may have used .txt expecting a single file, or whatever, and there are a million others.

Don’t get me wrong, I accept that there are legitimate use cases for bash, but I really can’t help but feel that anything longer than 3 lines (including #!) is better off in anything*.