Earlier quoted context omitted.
Which happens to be the fallacy of GNU/Linux desktop as well. The beauty of each desktop centric OS is the whole platform, the set of SDK languages, the respective frameworks for exposing the OS and hardware features that make the desktop experience unique, and IDE developer experience. If it is to run desktop agnostic apps, then anything can do.
There's always been some leeway in that. Both the original Mac OS and Windows had a variety of languages targeting it, but they tended to strive towards emulating the core SDK experience (if they weren't a wrapper around it). Unix had it different with there being no core experience in the first place -- X11 being a glorified terminal multiplexer plus xeyes. Whether it was the commercial Unices with OpenLook/NeWS vs…
I don't need such vision, it is how it would look like if all OSes happen to jungle browser instances, ChromeOS style, while a big chunk of applications runs on someone else's computer, abstracted via language runtimes.
The return to mainframe's timesharing days and very sad outcome for desktop computers, with the minimum experience common to all vendors.
Graphical APIs not able to take advantage of hardware, hardware support that takes years to have minimal APIs, drawing UIs pilling divs customized with CSS and JS to mimic visual behaviours.