Surely it would be better to fix the interoperability issues of the language? "Lets just add a single implementation of everything to the standard!" seems like quite a strange response to "users of the language are having trouble with interoperability due to false coupling."
Vue reactivity isn't compatible with Svelte, nor Angular.
As a counter example to your question, what if we all had competing implementations of the object primitive. Libraries would barely work with one another and would need an interop layer between them (just as reactivity layers do today!)
I'll admit I don't use JavaScript very often, but surely the state of polymorphism could be improved? For example, C++ recently added concepts, and most (modern) languages have some way to describe interfaces.
As to your counterexample, I agree with current JavaScript that would be a problem, but with good language support it would certainly be possible. For example, Rust (and C++?) have competing implementations of the global allocator, and must users will never notice.
The reactivity layers are all pretty tied into the hearts of the frameworks. There's no advantage to any framework to expose such a thing to end users to leverage a competing implementation.
As for polymorphism, even the current class syntax largely operates in the same way as the original prototypal inheritance mechanism, with a few exceptions in constructor behavior to support subclassing certain built-in objects.
You can pretty easily create run-time traits- like functions with prototpyes, the class construct is an expression whose resulting value can be passed around, mutated, etc.
For example, you can write a function that takes a class as an argument, and returns a new class that extends it.
I don't think the language hurts or hinders interop much? It has a wide range of tools that can adapt objects between different shapes, for when we do have two similar but different interfaces we are trying to bridge.
I struggle to see what more one could want. Do you have any specific features you think would help a massive ecosystem of packages be able to work together, when for example different packages have different Signal implementations?
Isn't this similar to small core vs large core debates you see in other projects, often where drivers are concerned? (ie question around where the coupling layer is materialized)
That's quite funny - yes, not only is this a horrible wilful backdoor, it is also a GPL violation since the backdoor is a derived work without included source / distributed not in "the preferred form for modification".
Sadly, it looks like xz-utils is actually public domain. Only some of the scripts (like xzgrep) were GPL. So it is and remains only a joke, not an actual violation, hilarious as that would have been to enforce