I'm not sure where you're coming from, but when I'm looking for a job, I pay attention to the tools that companies have picked, and if I get the chance to ask them, why. A company that picks good tools is a lot more attractive to me. All other thigns being equal, if I had to choose between a company that used JS, and one that used JS and one that used Elm, I would prefer the Elm one. I've never written a line of Elm before.

I'm willing and happy to learn new tools. I'm happy with hiking in flip-flops if that's all that's available, but I'd certainly choose hiking boots if given the choice. I suspect most "good" developers have the same attitude.