The closest thing we've had might be Lisp Machines, but that didn't work out.
That's why Emacs is still great: users can do whatever they want with it, and they do.
To a lower degree, we can sort of do that with workflow engines on the cloud (ex: Azure Logic Apps), or locally (ex: iOS Shortcuts).
As a user, I like being able to do that, but I do not like having to maintain my partially working thing, nor do I want to spend time ensuring it works as I expect (aka doing QA) outside of what I use it for today.
That's why Emacs is still great: users can do whatever they want with it, and they do.
To a lower degree, we can sort of do that with workflow engines on the cloud (ex: Azure Logic Apps), or locally (ex: iOS Shortcuts).
As a user, I like being able to do that, but I do not like having to maintain my partially working thing, nor do I want to spend time ensuring it works as I expect (aka doing QA) outside of what I use it for today.