I think this misses the point somewhat, I think even the typescript people will agree, yes, you CAN pick another language and get better type support ( amongst many other things ). But typescripts goal is to be a superset of javascript, which has resulted in many many libraries now shipping with typescript type definitions as officially supported things within libraries. Elm ( or any other client side language) simply hasn't had that kind of impact. Yes it does still have a bunch of problems inherited from the nature of javascript. Sure, you, as an individual might get good results with your tech choice.

So I think the main thing is typescript should make things better in the javascript world, but due to its ability to gradually adopt typescript syntax over javascript syntax you can live in a middle ground where it's not going to do much for you (or even make it worse).

Ultimately I think compiled WASM based languages are going to take over, but we aren't there yet.