LabVIEW
mklink interface
It wasn't before Windows 2000 that the NTSF driver actually supported something like hardlinks and took until Windows XP until they added Softlink support. The single API you found only got introduced in Windows 7. Anything else you want to do with soft and hardlinks under Windows such as querying the path such a "reparse point" points to, (official NTFS name for these things) still requires to call directly into the NTFS kernel driver.
And please note that even Windows 10 upgrade will get pretty badly hosed if you redirect system paths or even your home environment C:\Users\<your name> using these techniques yourself. This still doesn't sound to me like reparse points are first class citicens in the Windows environment like other file objects.
And while you are correct that calling an external command under Windows is a fairly expensive operation, the first question is always how often you intend to call this function. Unless you can foresee a possibility that a function is called many times in a tight loop, dismissing a solution based on real (and more often perceived) performance reasons is considered highly premature optimization!
I don't think overloading creat file/directory sounds like a good idea. The only thing in common by both is the desired path. Create file requires a permission, while create link requires the actual path the link should point to.
Overloading these functions would unneccessarily compllicate the node interface with very different parameters which are only neccessary in a specific mode of that function and totally meaningless for the other mode(s).
Of course since there is now an API to create a link, it's easiest to call that instead of mklink, but dismissing to call external commands principally is not really useful. Under Unix it is in fact the standard way of extending os funtionality. Instead of creating one application which tries to do everything more or less badly, ypu create little tools which do one thing good and call them all from your application,
