The new cross-plat runtimes and languages we could have had by now if JavaScript didn't have a stranglehold on the available browser-side language space... wow.
Probably barely working, super fragmented garbage. A standard that isn't optimal but works well enough is fantasic in comparison to everybody trying to make their own thing. And realistically, if something else would have emerged, people would whine about it just as much as they do about JS.
Nowadays, we can use pretty much any language we want and compile it down to JS/WebASM. And most just add some compile checks with TypeScript. Because that's good enough, and it works.
Another way is to appreciate the fact that we have an open-platform with a standards body that actually works (queue the responses about how it actually _doesn't_ work). I can write an app once and access it from any device and it will work today, and it will work 10 years from now.
No other platform has achieved what the web browsers have, so I think we might be doing something right.