If a platform does not actually support symlinks, and XP does not actually support symlinks for any usual definition of an operating system supporting a feature, then I'm not sure why pathlib is doing something wrong to make it work more reasonably in that case.

"os.symlink" is a NotImplementedError on Windows versions prior to Vista because the Windows API doesn't support CreateSymbolicLink. It doesn't make sense to just let the code try to run for all versions on all platforms but be wrapped in a try/catch block for the NotImplementedError.