Despite the now well-known security limitations of pickle, it is still used as a simple way (from the user PoV) to exchange arbitrary Python objects (see e.g. https://joblib.readthedocs.io/en/latest/persistence.html).  Such objects can sometimes include Paths as attributes, and it seems unfortunate that the presence of a Path makes the entire object (which may include many more things than just the Path) impossible to unpickle on a different OS (especially if unpickling into a PurePath keeps all the functionality that makes sense on that other OS).