disagree. the fact that i can see more and more support for fish and also start seeing support for elvish shows that those alternative shells have reached a scale meaningful enough that tool developers actually consider it worth their effort to support them. what else is that if not evidence that alternative shells have reached a meaningful scale?

before fish basically noone dared to break bash compatibility. zsh is bash on steroids and other incompatible shells like csh, tcsh, ksh, etc were dead ends in that they kept a niche status.

fish was the first shell to break out of that and actually get noticed and gain a following. i believe that all other alternative shells after fish were encouraged only because of fish's popularity.