The key problem I have with KIO is that it's doing something that should be done at a lower level so that every application can benefit.
As I see it, there are three classes of apps on Linux when it comes to file handling:
* Apps that can open remote files using one set of protocols (KIO-enabled apps).
* Apps that can open remote files using a different set of protocols (things that reinvent this wheel, like emacs in your example).
* Apps that can only work on local files.
So we get a situation where I can open a file on an SMB server using Kate, but I can't open the same file in Sublime Text. It makes for a terrible user experience.
The Mac makes it easy to mount filesystems, but it's kludgey compared to using UNC paths in Windows. This is the one feature that I really miss from Windows.
All I was saying originally was that KDE was the first Linux environment I used which came close to the level of broad support and integration you get from something like Windows, and in some cases it went beyond.
https://techbase.kde.org/Projects/KioFuse
Never tried it myself, so I don't know how well it works.
Anyway, I use emacs on both platforms and it handles all of this for me, so my dog retired from this game many years ago.