A language usually doesn't become worse with time, at least if the devs do a good job at improving it.
There are cases of new languages that looked better but didn't become mainstream because the ecosystem requires time to grow (and adoption, which creates a vicious cycle because adoption requires ecosystem to already be there)
I've toyed with WASM, creating a simple sudoku page, and it did take an empty page, added all the buttons, and then changed them upon user interaction.
I think, I also heard of the DOM modification limitations, but it's not a hard barrier afaik, there are just some cases where it can't
But still, doing something in (pure) WASM looks way harder than needed to me