Read the page, but essentially `/foo/bar/..` is not the same as `/foo`. It makes loads of things way more complicated than you'd expect, e.g. normalising paths now requires filesystem access, and normalising paths that only partially exist is really complicated.
Another annoying issue is symlink loops, but I'm not sure if Plan 9's solution solves that.
Another annoying issue is symlink loops, but I'm not sure if Plan 9's solution solves that.