It’s just my opinion, but the value proposition for any language/platform has to be more than pure joy. Adoption rarely has anything to with a language just being good. Devs are introduced to javascript first and once they learn to build with it convincing companies and devs to use a different language over anything that has the most momentum is a hard sell unless you can walk in to your managers office and show them real metrics on the money saved by using a language that is less error prone.
That being said. The better languages like elm/purescript must exist to bring good ideas back to mainstream languages. React and Rescript was build with that principle. React was built in SML originally and ported to javascript. Rescript used to be Reason that was basically Ocaml but changed to a more javascript syntax (typescript could be another example). Generally, speaking devs will use what is just there. And if it is too different… it will remain a niche language.
But still, Elm has inspired people to keep innovating in ML family languages which I’m glad about. In my opinion ML family syntax is easy to read with minimal noise. But that’s just my opinion (and I program in bracket languages all day).