> Given that this requirement is not universal and because a leading 
> slash controls other behaviors on platforms like Windows

Forward slash has no special meaning anywhere in the names of NT objects, such as memory Section objects (aka file-mapping objects) and registry Key objects. Only the file API translates forward slash to backslash, and that's only implemented for the sake of DOS compatibility in a few core functions that normalize and translate DOS paths.

Maybe you're thinking of the "Global\\" and "Session\\" prefixes for named kernel objects, which require a backslash since the name is really a handle-relative NT path. The session's object directory contains object symbolic links named "Global" and "Session". A name such as "Global\spam" resolves to "spam" in the global object directory, but "Global/spam", with forward slash, is just a regular name in the local directory.