What real word problem does bash solve over sh? Or tcsh over csh? Or ksh? Fish is the newest shell I’ve been using and it’s leaps and bounds better than dealing with posix syntax for the sake of unnecessary compatibility (if I need posix, I can run a posix shell without trouble). That said, fish is explicit about how the features it includes feel more like they should have evolved in th 90s, not the 2010s.

Asking forgiveness is better than asking permission. Innovation rarely looks like a sure bet prior to it unfolding.