Because working with things like GTK and QT is horrible compared to working with HTML/JS/CSS, for anything other than trivial things.
That said, it'd be cool to have native code generation from this though.
That said, it'd be cool to have native code generation from this though.
I'm a fan of React, but I have no desire to use it outside of the web, and maybe mobile (still on the fence there). For desktop, we have QT, which is truly an awesome native widget toolkit, with many thousands of man-years work in it, excellent cross-platform desktop coverage, along with pretty good accessibility standards.
Maybe the Qt apps have legitimate bugs but the fact is that native environments like Objective-C, and most likely this JavaScript environment, would both handle those issues very cleanly compared to Qt.
All the Qt apps I have touched (Google Earth comes to mind) have neither looked nor felt native on OS X, much like Swing and SWT apps don't at all feel native. Whereas all the best apps are written in native Cocoa.