This is exactly what Java was; you could run GUI apps on every platform and they'd work (and look) exactly the same.
The problem is, though, that every platform is actually different -- look and feel, UI conventions, feature-set, integration, etc. And Java solved this problem by introducing their own look and feel, UI conventions, etc that were completely different from the underlying platform. Sun wanted you to know that you were using a Java application. Users, on the other hand, were not too thrilled with this -- they wanted consistency across applications. Microsoft and Apple weren't too happy with another company trying to paper-over their entire platform so they didn't offer any help either.
The other problem was performance. Especially in those days, abstracting over the entire platform was pretty computationally expensive. Furthermore, since Java didn't render anything with the native UI it also didn't get much rendering help from the OS either.
> the different browsers regarding working together to identically implement JavaScript
They didn't work together; they simply copied features from each other in order to maintain compatibility with "the web". Netscape invented JavaScript. Microsoft copied it and added some features. Netscape copied those features and added some more. Microsoft repeated that. All the browser makers have written some code or API that never copied by everyone else.
It was really not that long ago that the standard process was formed and browser makers actually started working together.
The problem is, though, that every platform is actually different -- look and feel, UI conventions, feature-set, integration, etc. And Java solved this problem by introducing their own look and feel, UI conventions, etc that were completely different from the underlying platform. Sun wanted you to know that you were using a Java application. Users, on the other hand, were not too thrilled with this -- they wanted consistency across applications. Microsoft and Apple weren't too happy with another company trying to paper-over their entire platform so they didn't offer any help either.
The other problem was performance. Especially in those days, abstracting over the entire platform was pretty computationally expensive. Furthermore, since Java didn't render anything with the native UI it also didn't get much rendering help from the OS either.
> the different browsers regarding working together to identically implement JavaScript
They didn't work together; they simply copied features from each other in order to maintain compatibility with "the web". Netscape invented JavaScript. Microsoft copied it and added some features. Netscape copied those features and added some more. Microsoft repeated that. All the browser makers have written some code or API that never copied by everyone else.
It was really not that long ago that the standard process was formed and browser makers actually started working together.